/**
 * Skyseed V7 Component Styles
 * ===========================
 *
 * RULE: All styles MUST use only --ui-* semantic tokens.
 * NEVER use primitive tokens (--gray-500, --space-4) directly.
 *
 * Site-specific tokens (--site-*) are injected from site config
 * and override the base tokens when present.
 *
 * Load order: tokens.css THEN components.css
 */

/* ==========================================================================
   SITE-SPECIFIC TOKEN OVERRIDES
   These variables are injected from site config via inline <style>
   and override the base semantic tokens for full theme customization
   ========================================================================== */

:root {
  /* Map site tokens to semantic tokens (with fallbacks) */
  --ui-font-body: var(--site-font, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif);
  --ui-font-heading: var(--site-font-heading, var(--ui-font-body));
  --ui-bg: var(--site-page-bg, #ffffff);
  --ui-bg-subtle: var(--site-bg-subtle, #f8fafc);
  --ui-radius-md: var(--site-radius, 0.75rem);
  --ui-radius-btn: var(--site-radius-btn, 0.5rem);
  --ui-border: var(--site-border, #e2e8f0);
  --ui-shadow-card: var(--site-shadow, 0 1px 3px rgba(0,0,0,0.1));
  --ui-shadow-card-hover: var(--site-shadow-hover, 0 4px 6px rgba(0,0,0,0.1));
  --ui-text: var(--site-text, #1e293b);
  --ui-text-muted: var(--site-text-muted, #64748b);
}

/* ==========================================================================
   BASE RESET & DEFAULTS
   ========================================================================== */

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-family: var(--ui-font-body);
  font-size: var(--ui-text-body);
  line-height: var(--ui-leading);
  color: var(--ui-text);
  background: var(--ui-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main {
  flex: 1;
  padding: var(--ui-page-padding);
}

/* ==========================================================================
   TYPOGRAPHY
   ========================================================================== */

h1, h2, h3, h4, h5, h6 {
  font-family: var(--ui-font-heading);
  font-weight: var(--ui-weight-heading);
  line-height: var(--ui-leading-heading);
  color: var(--ui-text);
}

h1 { font-size: var(--ui-text-h1); }
h2 { font-size: var(--ui-text-h2); }
h3 { font-size: var(--ui-text-h3); }
h4 { font-size: var(--ui-text-h4); }
h5 { font-size: var(--ui-text-h5); }
h6 { font-size: var(--ui-text-h6); }

p {
  margin-bottom: var(--ui-gap-md);
}

a {
  color: var(--ui-link);
  text-decoration: none;
  transition: color var(--ui-transition-fast);
}

a:hover {
  color: var(--ui-link-hover);
}

a:active {
  color: var(--ui-link-active);
}

a:visited {
  color: var(--ui-link-visited);
}

code, pre {
  font-family: var(--ui-font-code);
  font-size: var(--ui-text-small);
}

code {
  background: var(--ui-bg-subtle);
  padding: var(--ui-padding-xs) var(--ui-padding-sm);
  border-radius: var(--ui-radius-sm);
}

pre {
  background: var(--ui-bg-subtle);
  padding: var(--ui-padding-md);
  border-radius: var(--ui-radius-md);
  overflow-x: auto;
}

/* ==========================================================================
   LAYOUT UTILITIES
   ========================================================================== */

.container {
  width: 100%;
  max-width: var(--ui-container-lg);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--ui-page-padding);
  padding-right: var(--ui-page-padding);
}

.container-sm { max-width: var(--ui-container-sm); }
.container-md { max-width: var(--ui-container-md); }
.container-xl { max-width: var(--ui-container-xl); }

/* Content Container - Primary content wrapper with unified width
   Uses --ui-page-max-width from tokens (default 1200px, can override via --site-container-width) */
.content-container {
  width: 100%;
  max-width: var(--ui-page-max-width);
  margin: 0 auto;
  padding: 0 clamp(16px, 4vw, 40px);
}

/* ==========================================================================
   V7 MOTHER CONTAINER (统一母体容器)
   All major layout sections (header, nav, content, footer) MUST use this
   to ensure consistent widths across the page.
   ========================================================================== */
.v7-container {
  width: 100%;
  max-width: var(--ui-page-max-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: clamp(16px, 4vw, 32px);
  padding-right: clamp(16px, 4vw, 32px);
}

/* Header inner layout - flex 布局，与 .v7-container 配合使用 */
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

/* Footer inner layout - 垂直布局，与 .v7-container 配合使用 */
.footer-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--ui-gap-md);
}

.section {
  margin-bottom: var(--ui-section-gap);
}

/* ==========================================================================
   V7 UNIFIED PROBLEM GRID (母体标准 - 类名大一统)
   所有算术题组件必须使用 v7- 前缀，禁止使用 001 特征类名
   ========================================================================== */

/* 题目网格：2列布局，呼吸感间距 */
.v7-problem-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem 1.5rem;
  margin: var(--ui-gap-lg) 0;
  padding: 1.5rem;
  background: var(--ui-bg-muted);
  border: 1px solid var(--ui-border);
  border-radius: var(--ui-radius-md);
}

/* 题目卡片：悬浮效果 */
.v7-problem-card {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 80px;
  padding: 1rem;
  background: var(--ui-bg);
  border: 1px solid var(--ui-border);
  border-radius: var(--ui-radius-sm);
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.v7-problem-card:hover {
  border-color: var(--site-primary, var(--ui-link));
  box-shadow: var(--ui-shadow-md);
}

/* 题号：内部左上角徽章 */
.v7-problem-number {
  position: absolute;
  top: 6px;
  left: 8px;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--site-primary, var(--ui-link));
  opacity: 0.8;
}

/* 题目内容区 */
.v7-problem-content {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  font-family: var(--ui-font-code);
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--ui-text);
}

/* 横式算术题 */
.v7-problem,
.v7-problem-horizontal {
  display: inline-flex;
  align-items: center;
  gap: 0.5em;
  font-size: 1.25rem;
  font-weight: 600;
}

/* 竖式算术题 */
.v7-problem-vertical {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  font-family: var(--ui-font-code);
  font-size: 1.25rem;
  line-height: 1.4;
}

.v7-problem-vertical .v7-operand,
.v7-problem-vertical .operand {
  text-align: right;
  min-width: 3ch;
}

.v7-problem-vertical .v7-operator-row,
.v7-problem-vertical .operator-row {
  display: flex;
  gap: 0.5em;
  border-bottom: 2px solid var(--ui-text);
  padding-bottom: 0.25em;
  margin-bottom: 0.25em;
}

/* ========== V7 ANSWER LINE - 全舰实线标准 ========== */
/* Web 模式：1.5px 实线，颜色随主题 */
.v7-answer-line {
  display: inline-block;
  min-width: 2.5em;
  height: 1.2em;
  border: none;
  border-bottom: 1.5px solid var(--site-primary, var(--ui-border));
  background: transparent;
  vertical-align: baseline;
}

/* 响应式：小屏幕单列 */
@media (max-width: 600px) {
  .v7-problem-grid {
    grid-template-columns: 1fr;
    gap: 1rem;
    padding: 1rem;
  }

  .v7-problem-content {
    font-size: 1.1rem;
  }
}

/* ==========================================================================
   SITE HEADER
   ========================================================================== */

.site-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--ui-padding-sm) var(--ui-padding-lg);
  background: var(--ui-bg-muted);
  border-bottom: 1px solid var(--ui-border-muted);
}

.site-title {
  font-size: var(--ui-text-h4);
  font-weight: var(--ui-weight-bold);
  color: var(--ui-text);
  text-decoration: none;
  transition: color var(--ui-transition-fast);
}

.site-title:hover {
  color: var(--ui-link);
}

/* ==========================================================================
   LANGUAGE SWITCHER
   ========================================================================== */

.language-switcher {
  position: relative;
  display: inline-block;
}

.language-switcher-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--ui-gap-sm);
  padding: var(--ui-padding-sm) var(--ui-padding-md);
  background: var(--ui-bg-subtle);
  border: 1px solid var(--ui-border);
  border-radius: var(--ui-radius-md);
  cursor: pointer;
  font-size: var(--ui-text-small);
  font-family: inherit;
  color: var(--ui-text);
  transition: background var(--ui-transition-fast), border-color var(--ui-transition-fast);
}

.language-switcher-btn:hover {
  background: var(--ui-state-hover-bg);
  border-color: var(--ui-border-hover);
}

.language-switcher-btn:focus {
  outline: none;
  box-shadow: var(--ui-state-focus-ring);
}

.language-dropdown {
  display: none;
  position: absolute;
  top: 100%; /* No gap - use padding-top for visual spacing */
  right: 0;
  padding-top: 6px; /* Visual gap while keeping hover connected */
  padding-bottom: 4px;
  background: var(--ui-bg);
  border: 1px solid var(--ui-border);
  border-radius: var(--ui-radius-md);
  box-shadow: var(--ui-shadow-dropdown);
  min-width: var(--ui-element-xs); /* Narrower for compact display */
  max-height: 85vh; /* Show all 20 languages */
  overflow-y: auto !important; /* Force scrollbar visibility */
  scrollbar-color: #3b82f6 #f3f4f6; /* Blue thumb on light gray track */
  scrollbar-width: thin; /* Firefox: show thin scrollbar */
  z-index: var(--ui-z-dropdown);
}

/* Webkit scrollbar styling (Chrome, Safari, Edge) */
.language-dropdown::-webkit-scrollbar {
  width: var(--ui-icon-2xs);
}

.language-dropdown::-webkit-scrollbar-track {
  background: #f3f4f6;
  border-radius: 4px;
}

.language-dropdown::-webkit-scrollbar-thumb {
  background: #3b82f6;
  border-radius: 4px;
}

.language-dropdown::-webkit-scrollbar-thumb:hover {
  background: #2563eb;
}

.language-dropdown.open,
.language-switcher:hover .language-dropdown,
.language-switcher:focus-within .language-dropdown {
  display: block;
}

.language-option {
  display: block;
  padding: 6px 12px; /* Compact padding for 20 languages */
  text-decoration: none;
  color: var(--ui-text);
  font-size: 0.8125rem; /* 13px - smaller for compact list */
  line-height: 1.3;
  white-space: nowrap;
  transition: background var(--ui-transition-fast);
}

.language-option:hover {
  background: var(--ui-state-hover-bg);
  color: var(--ui-text);
}

.language-option.current {
  background: var(--ui-state-selected-bg);
  font-weight: var(--ui-weight-medium);
}

/* RTL support for language dropdown */
[dir="rtl"] .language-dropdown {
  right: auto;
  left: 0;
}

/* ==========================================================================
   NAVIGATION / BREADCRUMBS
   ========================================================================== */

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--ui-gap-sm);
  padding: var(--ui-padding-sm) 0;
  font-size: var(--ui-text-small);
  color: var(--ui-text-muted);
}

.breadcrumb-separator {
  color: var(--ui-text-subtle);
}

.breadcrumb a {
  color: var(--ui-link);
}

.breadcrumb a:hover {
  color: var(--ui-link-hover);
}

/* ==========================================================================
   CARDS
   ========================================================================== */

.card {
  background: var(--ui-bg);
  border: 1px solid var(--ui-border-muted);
  border-radius: var(--ui-radius-lg);
  padding: var(--ui-padding-lg);
  box-shadow: var(--ui-shadow-sm);
}

.card-muted {
  background: var(--ui-bg-muted);
  border-color: var(--ui-border-subtle);
}

.card-header {
  margin-bottom: var(--ui-gap-md);
  padding-bottom: var(--ui-gap-md);
  border-bottom: 1px solid var(--ui-border-muted);
}

.card-title {
  font-size: var(--ui-text-h4);
  font-weight: var(--ui-weight-bold);
  margin: 0;
}

.card-body {
  /* Default body styling */
}

.card-footer {
  margin-top: var(--ui-gap-md);
  padding-top: var(--ui-gap-md);
  border-top: 1px solid var(--ui-border-muted);
}

/* ==========================================================================
   BUTTONS
   ========================================================================== */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--ui-gap-sm);
  padding: var(--ui-padding-sm) var(--ui-padding-md);
  font-family: inherit;
  font-size: var(--ui-text-body);
  font-weight: var(--ui-weight-medium);
  line-height: 1;
  text-decoration: none;
  border: 1px solid transparent;
  border-radius: var(--ui-radius-md);
  cursor: pointer;
  transition: background var(--ui-transition-fast),
              border-color var(--ui-transition-fast),
              box-shadow var(--ui-transition-fast);
}

.btn:focus {
  outline: none;
  box-shadow: var(--ui-state-focus-ring);
}

.btn:disabled {
  opacity: var(--ui-state-disabled-opacity);
  cursor: not-allowed;
}

/* Primary button */
.btn-primary {
  background: var(--ui-link);
  color: var(--ui-text-inverse);
  border-color: var(--ui-link);
}

.btn-primary:hover:not(:disabled) {
  background: var(--ui-link-hover);
  border-color: var(--ui-link-hover);
}

/* Secondary button */
.btn-secondary {
  background: var(--ui-bg);
  color: var(--ui-text);
  border-color: var(--ui-border);
}

.btn-secondary:hover:not(:disabled) {
  background: var(--ui-state-hover-bg);
  border-color: var(--ui-border-hover);
}

/* Ghost button */
.btn-ghost {
  background: transparent;
  color: var(--ui-link);
  border-color: transparent;
}

.btn-ghost:hover:not(:disabled) {
  background: var(--ui-state-hover-bg);
}

/* Button sizes */
.btn-sm {
  padding: var(--ui-padding-xs) var(--ui-padding-sm);
  font-size: var(--ui-text-small);
}

.btn-lg {
  padding: var(--ui-padding-md) var(--ui-padding-lg);
  font-size: var(--ui-text-large);
}

/* ==========================================================================
   FORM ELEMENTS
   ========================================================================== */

.input,
.select,
.textarea {
  width: 100%;
  padding: var(--ui-padding-sm) var(--ui-padding-md);
  font-family: inherit;
  font-size: var(--ui-text-body);
  color: var(--ui-text);
  background: var(--ui-bg);
  border: 1px solid var(--ui-border);
  border-radius: var(--ui-radius-md);
  transition: border-color var(--ui-transition-fast),
              box-shadow var(--ui-transition-fast);
}

.input:hover,
.select:hover,
.textarea:hover {
  border-color: var(--ui-border-hover);
}

.input:focus,
.select:focus,
.textarea:focus {
  outline: none;
  border-color: var(--ui-border-focus);
  box-shadow: var(--ui-state-focus-ring);
}

.input:disabled,
.select:disabled,
.textarea:disabled {
  background: var(--ui-bg-disabled);
  color: var(--ui-text-disabled);
  border-color: var(--ui-border-disabled);
  cursor: not-allowed;
}

.input-error,
.select-error,
.textarea-error {
  border-color: var(--ui-border-error);
}

.label {
  display: block;
  margin-bottom: var(--ui-gap-xs);
  font-size: var(--ui-text-small);
  font-weight: var(--ui-weight-medium);
  color: var(--ui-text);
}

.form-group {
  margin-bottom: var(--ui-gap-md);
}

.form-hint {
  margin-top: var(--ui-gap-xs);
  font-size: var(--ui-text-tiny);
  color: var(--ui-text-muted);
}

.form-error {
  margin-top: var(--ui-gap-xs);
  font-size: var(--ui-text-tiny);
  color: var(--ui-text-error);
}

/* ==========================================================================
   GRID (Category/Content Grids)
   ========================================================================== */

.grid {
  display: grid;
  gap: var(--ui-grid-gap);
}

.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

/* Responsive grid */
.grid-auto {
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
}

/* Category grid item */
.category-card {
  display: flex;
  flex-direction: column;
  gap: var(--ui-gap-sm);
  padding: var(--ui-padding-md);
  background: var(--ui-bg);
  border: 1px solid var(--ui-border-muted);
  border-radius: var(--ui-radius-lg);
  text-decoration: none;
  color: var(--ui-text);
  transition: border-color var(--ui-transition-fast),
              box-shadow var(--ui-transition-fast),
              transform var(--ui-transition-fast);
}

.category-card:hover {
  border-color: var(--ui-border-hover);
  box-shadow: var(--ui-shadow-md);
  transform: translateY(-2px);
}

.category-card-title {
  font-size: var(--ui-text-large);
  font-weight: var(--ui-weight-semibold);
  color: var(--ui-text);
}

.category-card-description {
  font-size: var(--ui-text-small);
  color: var(--ui-text-muted);
}

/* ==========================================================================
   FOOTER
   ========================================================================== */

.site-footer {
  margin-top: auto;
  padding: var(--ui-padding-lg);
  background: var(--ui-bg-muted);
  border-top: 1px solid var(--ui-border-muted);
  text-align: center;
  font-size: var(--ui-text-small);
  color: var(--ui-text-muted);
}

/* ==========================================================================
   DEBUG PANEL (Preview Mode Only)
   ========================================================================== */

.debug-panel {
  position: fixed;
  bottom: 0;
  right: 0;
  max-width: var(--ui-container-xs);
  max-height: 300px;
  overflow: auto;
  background: var(--ui-bg-inverse);
  color: var(--ui-text-inverse);
  padding: var(--ui-padding-sm);
  font-family: var(--ui-font-code);
  font-size: var(--ui-text-tiny);
  border-radius: var(--ui-radius-md) 0 0 0;
  z-index: var(--ui-z-tooltip);
}

.debug-panel pre {
  background: transparent;
  padding: 0;
  margin: 0;
  color: inherit;
}

/* ==========================================================================
   MESSAGES / ALERTS
   ========================================================================== */

.alert {
  padding: var(--ui-padding-md);
  border-radius: var(--ui-radius-md);
  margin-bottom: var(--ui-gap-md);
}

.alert-info {
  background: var(--ui-bg-accent);
  border: 1px solid var(--ui-border-focus);
  color: var(--ui-text);
}

.alert-success {
  background: var(--ui-bg-success);
  border: 1px solid var(--ui-border-success);
  color: var(--ui-text);
}

.alert-warning {
  background: var(--ui-bg-warning);
  border: 1px solid var(--ui-text-warning);
  color: var(--ui-text);
}

.alert-error {
  background: var(--ui-bg-error);
  border: 1px solid var(--ui-border-error);
  color: var(--ui-text);
}

/* ==========================================================================
   PRINT STYLES
   ========================================================================== */

@media print {
  .site-header,
  .site-footer,
  .language-switcher,
  .debug-panel,
  .btn {
    display: none !important;
  }

  main {
    padding: 0;
  }

  .card {
    border: 1px solid var(--ui-border) !important;
    box-shadow: none !important;
    break-inside: avoid;
  }

  a {
    color: var(--ui-text) !important;
  }

  a[href]::after {
    content: " (" attr(href) ")";
    font-size: var(--ui-text-tiny);
    color: var(--ui-text-muted);
  }

  /* Exclude QR code slot from URL injection */
  .print-qr-slot a[href]::after {
    content: none !important;
  }
}

/* ==========================================================================
   RTL (Right-to-Left) SUPPORT
   ========================================================================== */

[dir="rtl"] {
  text-align: right;
}

[dir="rtl"] .site-header {
  flex-direction: row-reverse;
}

[dir="rtl"] .breadcrumb {
  flex-direction: row-reverse;
}

[dir="rtl"] .btn {
  flex-direction: row-reverse;
}

/* ==========================================================================
   CONTENT PAGE (Worksheets, Generated Problems)
   ========================================================================== */

.content-page {
  background: var(--ui-bg);
  color: var(--ui-text);
}

.content-page h1 {
  color: var(--ui-text);
  border-bottom: 2px solid var(--ui-link);
  padding-bottom: var(--ui-gap-sm);
  margin-bottom: var(--ui-gap-lg);
}

.content-page h2 {
  color: var(--ui-link);
  margin-top: var(--ui-gap-xl);
  margin-bottom: var(--ui-gap-md);
}

/* Skill Description - explains what users will practice */
.skill-description {
  background: var(--ui-bg-muted);
  border-left: 4px solid var(--ui-link);
  padding: var(--ui-padding-md) var(--ui-padding-lg);
  margin-bottom: var(--ui-gap-lg);
  border-radius: 0 var(--ui-radius) var(--ui-radius) 0;
}

.skill-description p {
  margin: 0;
  color: var(--ui-text-muted);
  font-size: var(--ui-text-body);
  line-height: 1.6;
}

.content-body {
  margin-bottom: var(--ui-gap-lg);
}

/* ==========================================================================
   PROBLEM GRID (Generated Math Problems)
   ========================================================================== */

/* Problem Grid - Clean, borderless American worksheet style */
.problem-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--ui-gap-lg) var(--ui-gap-xl);
  margin: var(--ui-gap-lg) 0;
  padding: var(--ui-padding-lg) 0;
}

/* Problem Card - No borders, clean worksheet look */
.problem-card {
  background: transparent;
  border: none;
  padding: var(--ui-padding-md);
  text-align: center;
}

.problem {
  font-family: var(--ui-font-body);
  font-size: var(--ui-text-h4);
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 1em;
}

.problem-horizontal {
  gap: 0.75em;
}

.operand {
  min-width: 2.5em;
  text-align: center;
  padding: 0 0.5em;
  font-variant-numeric: tabular-nums;
}

.operator {
  color: var(--ui-link);
  font-weight: var(--ui-weight-bold);
  padding: 0 0.5em;
  font-size: 1.1em;
}

.equals {
  color: var(--ui-text-muted);
  padding: 0 0.5em;
  font-size: 1.1em;
}

/* Legacy answer-blank - 保留兼容性，实际使用 v7-answer-line */
.answer-blank {
  display: inline-block;
  min-width: 2.5em;
  border-bottom: 1.5px solid var(--site-primary, var(--ui-border));
  vertical-align: baseline;
}

/* Grid problem (Sudoku, etc.) */
.grid-problem {
  font-family: var(--ui-font-code);
}

.generic-problem {
  font-size: var(--ui-text-small);
  text-align: left;
}

/* ==========================================================================
   ANSWER KEY
   ========================================================================== */

.answer-key {
  margin-top: var(--ui-gap-xl);
  padding: var(--ui-padding-md);
  background: var(--ui-bg-muted);
  border-radius: var(--ui-radius-lg);
}

.answer-key summary {
  cursor: pointer;
  font-weight: var(--ui-weight-bold);
  color: var(--ui-link);
}

.answer-key ol {
  margin-top: var(--ui-gap-md);
  padding-left: var(--ui-padding-lg);
}

/* ==========================================================================
   SET SWITCHER (Problem Set Navigator)
   ========================================================================== */

.set-switcher {
  display: flex;
  flex-wrap: wrap;
  gap: var(--ui-gap-sm);
  margin: var(--ui-gap-lg) 0;
  padding: var(--ui-padding-md);
  background: var(--ui-bg-muted);
  border-radius: var(--ui-radius-lg);
}

.set-switcher-label {
  width: 100%;
  font-weight: var(--ui-weight-bold);
  margin-bottom: var(--ui-gap-sm);
  color: var(--ui-text);
}

.set-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: var(--ui-icon-2xl);
  height: 40px;
  border: 2px solid var(--ui-border);
  border-radius: var(--ui-radius-lg);
  background: var(--ui-bg);
  color: var(--ui-text);
  text-decoration: none;
  font-weight: var(--ui-weight-bold);
  transition: border-color var(--ui-transition-fast),
              background var(--ui-transition-fast);
}

.set-btn:hover {
  border-color: var(--ui-link);
  background: var(--ui-bg-accent);
}

.set-btn.current {
  background: var(--ui-link);
  border-color: var(--ui-link);
  color: var(--ui-text-inverse);
}

[dir="rtl"] .set-switcher {
  flex-direction: row-reverse;
}

/* ==========================================================================
   THEME SWITCHER
   ========================================================================== */

.theme-switcher {
  display: flex;
  gap: var(--ui-gap-sm);
  margin: var(--ui-gap-lg) 0;
  padding: var(--ui-padding-md);
  background: var(--ui-bg-muted);
  border-radius: var(--ui-radius-lg);
  align-items: center;
  flex-wrap: wrap;
}

.theme-switcher-label {
  font-weight: var(--ui-weight-bold);
  margin-right: var(--ui-gap-sm);
  color: var(--ui-text);
}

.theme-btn {
  padding: var(--ui-padding-sm) var(--ui-padding-md);
  border: 2px solid var(--ui-border);
  border-radius: var(--ui-radius-md);
  background: var(--ui-bg);
  color: var(--ui-text);
  text-decoration: none;
  font-size: var(--ui-text-small);
  transition: border-color var(--ui-transition-fast),
              background var(--ui-transition-fast);
}

.theme-btn:hover {
  border-color: var(--ui-link);
  background: var(--ui-bg-muted);
}

.theme-btn.current {
  background: var(--ui-link);
  border-color: var(--ui-link);
  color: var(--ui-text-inverse);
}

/* ==========================================================================
   ACTION BUTTONS (Random, Print)
   ========================================================================== */

.action-buttons {
  display: flex;
  gap: var(--ui-gap-md);
  margin: var(--ui-gap-lg) 0;
  flex-wrap: wrap;
}

.action-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--ui-gap-sm);
  padding: var(--ui-padding-sm) var(--ui-padding-lg);
  border: 2px solid var(--ui-border);
  border-radius: var(--ui-radius-lg);
  background: var(--ui-bg);
  color: var(--ui-text);
  text-decoration: none;
  font-weight: var(--ui-weight-semibold);
  cursor: pointer;
  transition: border-color var(--ui-transition-fast),
              background var(--ui-transition-fast),
              color var(--ui-transition-fast);
  font-size: var(--ui-text-small);
  font-family: inherit;
}

.action-btn:hover {
  border-color: var(--ui-link);
  background: var(--ui-bg-accent);
  color: var(--ui-link);
}

.action-btn.primary {
  background: var(--ui-link);
  border-color: var(--ui-link);
  color: var(--ui-text-inverse);
}

.action-btn.primary:hover {
  background: var(--ui-link-hover);
  border-color: var(--ui-link-hover);
  color: var(--ui-text-inverse);
}

.action-btn svg {
  width: calc(var(--ui-icon-md) + 2px);
  height: 18px;
}

/* ==========================================================================
   RANDOM MODE INDICATOR
   ========================================================================== */

.random-mode-indicator {
  background: var(--ui-bg-warning);
  border: 1px solid var(--ui-text-warning);
  color: var(--ui-text);
  padding: var(--ui-padding-sm) var(--ui-padding-md);
  border-radius: var(--ui-radius-lg);
  margin: var(--ui-gap-md) 0;
  font-size: var(--ui-text-small);
}

/* ==========================================================================
   BREADCRUMBS (Alternative Style)
   ========================================================================== */

.breadcrumbs {
  margin-bottom: var(--ui-gap-md);
  font-size: var(--ui-text-small);
}

.breadcrumbs ol {
  display: flex;
  flex-wrap: wrap;
  list-style: none;
  padding: 0;
  margin: 0;
  gap: var(--ui-gap-xs);
}

.breadcrumbs li {
  display: flex;
  align-items: center;
}

.breadcrumbs li:not(:last-child)::after {
  content: "/";
  margin-left: var(--ui-gap-xs);
  color: var(--ui-text-subtle);
}

.breadcrumbs a {
  color: var(--ui-link);
}

.breadcrumbs a:hover {
  color: var(--ui-link-hover);
}

.breadcrumbs [aria-current="page"] {
  color: var(--ui-text-muted);
}

/* ==========================================================================
   HOME PAGE
   ========================================================================== */

.home-page {
  max-width: var(--ui-page-max-width);
  margin: 0 auto;
}

.dimension-section {
  margin-bottom: var(--ui-section-gap);
}

.dimension-title {
  display: flex;
  align-items: center;
  gap: var(--ui-gap-sm);
  margin-bottom: var(--ui-gap-md);
}

.badge-primary {
  display: inline-block;
  padding: var(--ui-padding-xs) var(--ui-padding-sm);
  font-size: var(--ui-text-tiny);
  font-weight: var(--ui-weight-medium);
  background: var(--ui-link);
  color: var(--ui-text-inverse);
  border-radius: var(--ui-radius-full);
}

.node-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: var(--ui-gap-md);
}

.node-card {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--ui-padding-md);
  background: var(--ui-bg);
  border: 1px solid var(--ui-border-muted);
  border-radius: var(--ui-radius-md);
  text-decoration: none;
  transition: border-color var(--ui-transition-fast),
              box-shadow var(--ui-transition-fast),
              transform var(--ui-transition-fast);
}

.node-card:hover {
  border-color: var(--ui-link);
  box-shadow: var(--ui-shadow-sm);
  transform: translateY(-1px);
}

.node-name {
  font-weight: var(--ui-weight-medium);
  color: var(--ui-text);
}

.node-card:hover .node-name {
  color: var(--ui-link);
}

.dimension-info {
  margin-top: var(--ui-gap-sm);
  font-size: var(--ui-text-small);
  color: var(--ui-text-muted);
}

/* ==========================================================================
   CATEGORY PAGE
   ========================================================================== */

.category-page {
  max-width: var(--ui-page-max-width);
  margin: 0 auto;
}

.sub-categories {
  margin: var(--ui-gap-lg) 0;
}

.sub-categories ul {
  list-style: none;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: var(--ui-gap-sm);
}

.sub-categories li {
  padding: var(--ui-padding-sm) var(--ui-padding-md);
  background: var(--ui-bg-muted);
  border-radius: var(--ui-radius-md);
}

.sub-categories a {
  color: var(--ui-link);
}

.content-list {
  margin: var(--ui-gap-lg) 0;
}

.content-card {
  padding: var(--ui-padding-md);
  margin-bottom: var(--ui-gap-md);
  background: var(--ui-bg);
  border: 1px solid var(--ui-border-muted);
  border-radius: var(--ui-radius-md);
}

.content-card h3 {
  margin-bottom: var(--ui-gap-sm);
}

.content-card p {
  color: var(--ui-text-muted);
  margin: 0;
}

/* ==========================================================================
   TOOL PAGE
   ========================================================================== */

.tool-page {
  max-width: var(--ui-container-md);
  margin: 0 auto;
}

.tool-config {
  margin: var(--ui-gap-lg) 0;
  padding: var(--ui-padding-lg);
  background: var(--ui-bg-muted);
  border-radius: var(--ui-radius-lg);
}

.tool-output {
  margin: var(--ui-gap-lg) 0;
}

/* ==========================================================================
   SEARCH PAGE
   ========================================================================== */

.search-page {
  max-width: var(--ui-container-md);
  margin: 0 auto;
}

.search-form {
  display: flex;
  gap: var(--ui-gap-sm);
  margin: var(--ui-gap-lg) 0;
}

.search-form input[type="search"] {
  flex: 1;
  padding: var(--ui-padding-sm) var(--ui-padding-md);
  font-family: inherit;
  font-size: var(--ui-text-body);
  border: 1px solid var(--ui-border);
  border-radius: var(--ui-radius-md);
  background: var(--ui-bg);
  color: var(--ui-text);
}

.search-form input[type="search"]:focus {
  outline: none;
  border-color: var(--ui-border-focus);
  box-shadow: var(--ui-state-focus-ring);
}

.search-form button {
  padding: var(--ui-padding-sm) var(--ui-padding-lg);
  background: var(--ui-link);
  color: var(--ui-text-inverse);
  border: none;
  border-radius: var(--ui-radius-md);
  cursor: pointer;
  font-family: inherit;
  font-size: var(--ui-text-body);
  font-weight: var(--ui-weight-medium);
  transition: background var(--ui-transition-fast);
}

.search-form button:hover {
  background: var(--ui-link-hover);
}

.search-results {
  margin-top: var(--ui-gap-lg);
}

.results-count {
  color: var(--ui-text-muted);
  margin-bottom: var(--ui-gap-md);
}

.search-result {
  padding: var(--ui-padding-md);
  margin-bottom: var(--ui-gap-md);
  border-bottom: 1px solid var(--ui-border-muted);
}

.search-result h2 {
  font-size: var(--ui-text-large);
  margin-bottom: var(--ui-gap-xs);
}

.search-result p {
  color: var(--ui-text-muted);
  margin: 0;
}

/* ==========================================================================
   STATISTICS PROBLEMS
   ========================================================================== */

.statistics-problem {
  text-align: left;
  font-size: var(--ui-text-body);
}

.data-context {
  font-size: var(--ui-text-small);
  color: var(--ui-text-muted);
  margin-bottom: var(--ui-gap-sm);
  padding: var(--ui-padding-xs) var(--ui-padding-sm);
  background: var(--ui-bg-subtle);
  border-radius: var(--ui-radius-sm);
}

.data-set {
  display: flex;
  align-items: baseline;
  gap: var(--ui-gap-sm);
  margin-bottom: var(--ui-gap-md);
  padding: var(--ui-padding-sm);
  background: var(--ui-bg-muted);
  border-radius: var(--ui-radius-md);
}

.data-label {
  font-weight: var(--ui-weight-semibold);
  color: var(--ui-text-muted);
}

.data-values {
  font-family: var(--ui-font-code);
  font-size: var(--ui-text-large);
  color: var(--ui-text);
}

.statistics-question {
  font-weight: var(--ui-weight-medium);
  color: var(--ui-link);
  padding: var(--ui-padding-sm);
  border-left: 3px solid var(--ui-link);
  background: var(--ui-bg-accent);
  border-radius: 0 var(--ui-radius-sm) var(--ui-radius-sm) 0;
}

.chart-container {
  display: flex;
  justify-content: center;
  margin: var(--ui-gap-md) 0;
  padding: var(--ui-padding-md);
  background: var(--ui-bg-muted);
  border-radius: var(--ui-radius-md);
}

.chart-container svg {
  max-width: 100%;
  height: auto;
}

.bar-graph-svg {
  font-family: var(--ui-font-body);
}

.compare-data {
  display: flex;
  flex-direction: column;
  gap: var(--ui-gap-sm);
  margin-bottom: var(--ui-gap-md);
}

.data-group {
  padding: var(--ui-padding-sm);
  background: var(--ui-bg-muted);
  border-radius: var(--ui-radius-md);
}

.options-list {
  list-style: none;
  padding: 0;
  margin: var(--ui-gap-sm) 0;
  display: flex;
  flex-wrap: wrap;
  gap: var(--ui-gap-sm);
}

.option-item {
  padding: var(--ui-padding-xs) var(--ui-padding-md);
  border: 1px solid var(--ui-border);
  border-radius: var(--ui-radius-full);
  font-size: var(--ui-text-small);
}

/* ==========================================================================
   GEOMETRY PROBLEMS
   ========================================================================== */

.geometry-problem {
  text-align: center;
}

.shape-container {
  display: flex;
  justify-content: center;
  margin: var(--ui-gap-md) 0;
  padding: var(--ui-padding-lg);
  background: var(--ui-bg-muted);
  border-radius: var(--ui-radius-lg);
}

.shape-container svg {
  max-width: var(--ui-element-sm);
  height: auto;
}

.geometry-question {
  font-weight: var(--ui-weight-medium);
  color: var(--ui-text);
  margin: var(--ui-gap-md) 0;
}

.angle-display {
  font-size: var(--ui-text-h3);
  font-weight: var(--ui-weight-bold);
  color: var(--ui-link);
  text-align: center;
  padding: var(--ui-padding-md);
  background: var(--ui-bg-accent);
  border-radius: var(--ui-radius-md);
  margin-bottom: var(--ui-gap-md);
}

/* ==========================================================================
   MEASUREMENT PROBLEMS
   ========================================================================== */

.measurement-problem {
  text-align: center;
}

.ruler-container {
  display: flex;
  justify-content: center;
  margin: var(--ui-gap-md) 0;
  padding: var(--ui-padding-lg);
  background: var(--ui-bg-muted);
  border-radius: var(--ui-radius-lg);
}

.ruler-container svg {
  max-width: 100%;
  height: auto;
}

.measurement-question {
  font-weight: var(--ui-weight-medium);
  color: var(--ui-text);
  margin: var(--ui-gap-md) 0;
}

.comparison-items {
  display: flex;
  justify-content: center;
  gap: var(--ui-gap-lg);
  margin: var(--ui-gap-md) 0;
}

.comparison-item {
  padding: var(--ui-padding-md);
  background: var(--ui-bg-muted);
  border-radius: var(--ui-radius-md);
  text-align: center;
}

.comparison-item strong {
  display: block;
  margin-bottom: var(--ui-gap-xs);
  color: var(--ui-link);
}

/* ==========================================================================
   SUDOKU PROBLEMS
   ========================================================================== */

.sudoku-problem {
  text-align: center;
}

.sudoku-grid {
  display: inline-grid;
  margin: var(--ui-gap-md) auto;
  background: var(--sudoku-cell-bg, var(--ui-bg));
  box-shadow: var(--ui-shadow-md);
  border: var(--sudoku-border-box, 3px) solid var(--sudoku-border-color-box, var(--ui-text));
  border-radius: var(--ui-radius-sm);
}

/* Grid size variations */
.sudoku-grid[data-grid-size="4"] { grid-template-columns: repeat(4, var(--sudoku-cell-size, 44px)); }
.sudoku-grid[data-grid-size="6"] { grid-template-columns: repeat(6, var(--sudoku-cell-size, 44px)); }
.sudoku-grid[data-grid-size="9"] { grid-template-columns: repeat(9, var(--sudoku-cell-size, 44px)); }
.sudoku-grid[data-grid-size="16"] { grid-template-columns: repeat(16, 28px); }
.sudoku-grid[data-grid-size="25"] { grid-template-columns: repeat(25, 22px); }
.sudoku-grid[data-grid-size="36"] { grid-template-columns: repeat(36, 16px); }

/* Large grid cell size overrides - fit in ~600px width */
.sudoku-grid[data-grid-size="16"] .sudoku-cell { width: 32px; height: 32px; font-size: 14px; }
.sudoku-grid[data-grid-size="25"] .sudoku-cell { width: 22px; height: 22px; font-size: 10px; }
.sudoku-grid[data-grid-size="36"] .sudoku-cell { width: 15px; height: 15px; font-size: 8px; }

/* Update grid-template-columns to match cell sizes */
.sudoku-grid[data-grid-size="16"] { grid-template-columns: repeat(16, 32px); } /* 512px + borders */
.sudoku-grid[data-grid-size="25"] { grid-template-columns: repeat(25, 22px); } /* 550px + borders */
.sudoku-grid[data-grid-size="36"] { grid-template-columns: repeat(36, 15px); } /* 540px + borders */

/* Force single column layout for large grids using :has() */
.v7-problem-grid:has(.sudoku-grid[data-grid-size="16"]),
.v7-problem-grid:has(.sudoku-grid[data-grid-size="25"]),
.v7-problem-grid:has(.sudoku-grid[data-grid-size="36"]) {
  grid-template-columns: 1fr !important;
  max-width: 700px;
  margin: 0 auto;
}

/* Center large grids */
.v7-problem-card:has(.sudoku-grid[data-grid-size="16"]),
.v7-problem-card:has(.sudoku-grid[data-grid-size="25"]),
.v7-problem-card:has(.sudoku-grid[data-grid-size="36"]) {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.sudoku-cell {
  width: var(--sudoku-cell-size, 44px);
  height: var(--sudoku-cell-size, 44px);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--sudoku-cell-font, var(--ui-font-code));
  font-size: var(--sudoku-cell-font-size, 20px);
  font-weight: var(--sudoku-cell-font-weight, 600);
  background: var(--sudoku-cell-bg, var(--ui-bg));
  color: var(--sudoku-cell-text-user, var(--ui-link));
  border: var(--sudoku-border-thin, 1px) solid var(--sudoku-border-color-light, var(--ui-border-muted));
  cursor: pointer;
  user-select: none;
  transition: background var(--ui-transition-fast), border-color var(--ui-transition-fast);
}

/* Cell state: Given clue */
.sudoku-cell.given {
  background: var(--sudoku-cell-bg-given, var(--ui-bg-subtle));
  color: var(--sudoku-cell-text-given, var(--ui-text));
  cursor: default;
}

/* Cell state: Empty */
.sudoku-cell.empty {
  color: transparent;
}

/* Cell state: Selected */
.sudoku-cell.selected {
  background: var(--sudoku-cell-bg-selected, #dbeafe);
  border-color: var(--sudoku-primary, #2563eb);
}

/* Cell state: Highlighted (same number) */
.sudoku-cell.highlight {
  background: var(--sudoku-cell-bg-highlight, #e0f2fe);
}

/* Cell state: Error */
.sudoku-cell.error {
  background: var(--sudoku-cell-bg-error, #fee2e2);
  color: var(--sudoku-cell-text-error, #dc2626);
}

/* Box boundary borders (attribute-based for all grid sizes) */
.sudoku-cell[data-box-top="true"] {
  border-top: var(--sudoku-border-box, 3px) solid var(--sudoku-border-color-box, var(--ui-text));
}
.sudoku-cell[data-box-left="true"] {
  border-left: var(--sudoku-border-box, 3px) solid var(--sudoku-border-color-box, var(--ui-text));
}
.sudoku-cell[data-box-bottom="true"] {
  border-bottom: var(--sudoku-border-box, 3px) solid var(--sudoku-border-color-box, var(--ui-text));
}
.sudoku-cell[data-box-right="true"] {
  border-right: var(--sudoku-border-box, 3px) solid var(--sudoku-border-color-box, var(--ui-text));
}

/* Pencil marks (candidates) */
.sudoku-cell .pencil-marks {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0;
  font-size: 9px;
  color: var(--sudoku-cell-text-pencil, var(--ui-text-subtle));
  line-height: 1;
}

/* Legacy table-based grid support */
.sudoku-grid td {
  width: var(--sudoku-cell-size, 44px);
  height: var(--sudoku-cell-size, 44px);
  text-align: center;
  vertical-align: middle;
  font-family: var(--sudoku-cell-font, var(--ui-font-code));
  font-size: var(--sudoku-cell-font-size, 20px);
  font-weight: var(--sudoku-cell-font-weight, 600);
  border: var(--sudoku-border-thin, 1px) solid var(--sudoku-border-color-light, var(--ui-border-muted));
}

.sudoku-grid td.given {
  background: var(--sudoku-cell-bg-given, var(--ui-bg-subtle));
  color: var(--sudoku-cell-text-given, var(--ui-text));
}

.sudoku-grid td.empty {
  background: var(--sudoku-cell-bg, var(--ui-bg));
  color: transparent;
}

/* Legacy 3x3 box borders for 9x9 grids */
.sudoku-grid tr:nth-child(3n) td {
  border-bottom: var(--sudoku-border-box, 3px) solid var(--sudoku-border-color-box, var(--ui-text));
}

.sudoku-grid td:nth-child(3n) {
  border-right: var(--sudoku-border-box, 3px) solid var(--sudoku-border-color-box, var(--ui-text));
}

.sudoku-grid tr:first-child td {
  border-top: var(--sudoku-border-box, 3px) solid var(--sudoku-border-color-box, var(--ui-text));
}

.sudoku-grid td:first-child {
  border-left: var(--sudoku-border-box, 3px) solid var(--sudoku-border-color-box, var(--ui-text));
}

/* Difficulty badge colors */
.difficulty-badge.easy { background: var(--sudoku-easy-color, #22c55e); color: white; }
.difficulty-badge.medium { background: var(--sudoku-medium-color, #f59e0b); color: white; }
.difficulty-badge.hard { background: var(--sudoku-hard-color, #ef4444); color: white; }
.difficulty-badge.expert { background: var(--sudoku-expert-color, #8b5cf6); color: white; }

/* Sudoku Timer */
.sudoku-timer {
  display: inline-flex;
  align-items: center;
  gap: var(--ui-gap-sm);
  font-family: var(--sudoku-timer-font, 'Poppins', var(--ui-font-heading));
  font-size: var(--sudoku-timer-font-size, 1.5rem);
  font-weight: 500;
  color: var(--sudoku-timer-color, var(--ui-text));
  background: var(--sudoku-timer-bg, var(--ui-bg-muted));
  padding: var(--ui-padding-sm) var(--ui-padding-md);
  border-radius: var(--ui-radius-lg);
}

.sudoku-timer-icon {
  width: 1.25em;
  height: 1.25em;
  color: var(--sudoku-primary, var(--ui-link));
}

/* Number input buttons */
.sudoku-numpad {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: var(--ui-gap-xs);
  margin-top: var(--ui-gap-md);
  max-width: 280px;
  margin-inline: auto;
}

.sudoku-numpad button {
  padding: var(--ui-padding-sm);
  font-size: var(--ui-text-lg);
  font-weight: 600;
  background: var(--ui-bg-muted);
  border: 1px solid var(--ui-border);
  border-radius: var(--ui-radius-md);
  cursor: pointer;
  transition: all var(--ui-transition-fast);
}

.sudoku-numpad button:hover {
  background: var(--ui-state-hover-bg);
  border-color: var(--sudoku-primary, var(--ui-link));
}

.sudoku-numpad button:active {
  background: var(--ui-state-active-bg);
}

/* ==========================================================================
   PRINT UTILITIES
   ========================================================================== */

/* QR Code Print Slot - Hidden on screen, visible on print */
.print-qr-slot {
  display: none;
}

/* Print-only elements - Hidden on screen */
.print-only {
  display: none !important;
}

/* Screen-only elements - Use @media print in print.css to hide */
.screen-only {
  display: block;
}

/* ==========================================================================
   WORDSEARCH PROBLEMS
   ========================================================================== */

.wordsearch-problem {
  text-align: left;
}

.wordsearch-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--ui-gap-md);
}

.wordsearch-title {
  font-size: var(--ui-text-large);
  font-weight: var(--ui-weight-bold);
  color: var(--ui-text);
}

.theme-badge {
  padding: var(--ui-padding-xs) var(--ui-padding-sm);
  background: var(--ui-link);
  color: var(--ui-text-inverse);
  border-radius: var(--ui-radius-full);
  font-size: var(--ui-text-tiny);
  font-weight: var(--ui-weight-medium);
}

.wordsearch-container {
  display: flex;
  gap: var(--ui-gap-lg);
  flex-wrap: wrap;
}

.wordsearch-grid-wrapper {
  overflow-x: auto;
}

.wordsearch-grid {
  border-collapse: collapse;
  font-family: var(--ui-font-code);
}

.wordsearch-grid td.wordsearch-cell {
  width: var(--ui-icon-xl);
  height: 28px;
  text-align: center;
  vertical-align: middle;
  font-size: var(--ui-text-body);
  font-weight: var(--ui-weight-bold);
  border: 1px solid var(--ui-border-muted);
  background: var(--ui-bg);
  transition: background var(--ui-transition-fast);
}

.wordsearch-grid td.wordsearch-cell:hover {
  background: var(--ui-bg-accent);
}

.wordsearch-wordlist {
  flex: 0 0 auto;
}

.wordsearch-wordlist h4 {
  margin: 0 0 var(--ui-gap-sm);
  font-size: var(--ui-text-small);
  color: var(--ui-text-muted);
}

.word-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: var(--ui-gap-xs);
}

.word-item {
  font-size: var(--ui-text-small);
}

.word-item label {
  display: flex;
  align-items: center;
  gap: var(--ui-gap-sm);
  cursor: pointer;
}

.word-checkbox:checked + * {
  text-decoration: line-through;
  color: var(--ui-text-muted);
}

.wordsearch-instructions {
  margin-top: var(--ui-gap-md);
  font-size: var(--ui-text-small);
  color: var(--ui-text-muted);
  font-style: italic;
}

/* ==========================================================================
   ERROR BLOCK
   ========================================================================== */

.error-block {
  padding: var(--ui-padding-lg);
  background: var(--ui-bg-error);
  border: 1px solid var(--ui-border-error);
  border-radius: var(--ui-radius-lg);
  color: var(--ui-text);
}

.error-block strong {
  color: var(--ui-text-error);
}

/* ==========================================================================
   PRINT HEADER (Name/Class/Date - hidden in web, shown in print)
   ========================================================================== */

.print-header {
  display: none;
}

/* ==========================================================================
   CONTENT PAGE PRINT STYLES
   ========================================================================== */

@media print {
  /* Print layout - allow multiple pages */
  html, body {
    height: auto;
    overflow: visible;
    margin: 0;
    padding: 0;
    padding-bottom: 0 !important;
  }

  /* Page setup - DEVIL COMPRESSION: 0.5cm margins */
  @page {
    size: A4;
    margin: 0.5cm !important;
  }

  /* TOTAL CLEANUP: Hide ALL navigation, footer, breadcrumbs */
  footer {
    display: none !important;
  }

  .nav,
  .main-nav,
  .breadcrumb,
  .breadcrumbs,
  .nav-breadcrumbs,
  .site-header,
  .site-footer,
  .set-switcher,
  .theme-switcher,
  .action-buttons,
  .random-mode-indicator,
  .worksheet-header,
  .section-header,
  .generated-content > .section-header,
  .content-page h1,
  .worksheet-description,
  .worksheet-article > header {
    display: none !important;
  }

  /* Show print header - STACKED layout (title + meta on separate lines) */
  .print-header {
    display: block !important;
    margin: 0 0 6pt 0 !important;
    padding: 0 0 4pt 0;
    border-bottom: 1pt solid #000;
  }

  /* Print title - first line, left aligned */
  .print-title {
    font-size: 12pt;
    font-weight: bold;
    color: #000;
    margin: 0 0 2pt 0 !important;
    padding: 0;
    text-align: left;
    line-height: 1.2;
  }

  /* Print meta (Name/Date) - second line, right aligned */
  .print-meta {
    display: flex;
    justify-content: flex-end;
    gap: 10pt;
    font-size: 8pt;
    color: #000;
    margin: 0;
  }

  .print-field {
    display: inline-flex;
    align-items: baseline;
    gap: 2pt;
  }

  .print-line {
    display: inline-block;
    width: 50pt;
    border-bottom: 0.5pt solid #000;
    vertical-align: baseline;
  }

  /* Content page - force single page */
  .content-page {
    padding: 0;
    margin: 0;
    max-width: 100%;
    max-height: 100vh;
    overflow: hidden;
  }

  .worksheet-article {
    padding: 0;
    margin: 0;
  }

  /* Hide headings - title is in print-header */
  .content-page h1,
  .content-page h2,
  .skill-description {
    display: none !important;
  }

  /* Generated content - no extra space */
  .generated-content {
    padding: 0;
    margin: 0;
  }

  /* Problem grid - DEVIL COMPRESSION: 2pt row-gap, 15pt column-gap */
  .problem-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    row-gap: 2pt !important;
    column-gap: 15pt !important;
    max-width: 100%;
    margin: 0;
    padding: 0;
    border: none !important;
    background: none !important;
    border-radius: 0 !important;
  }

  /* Problem card - DEVIL COMPRESSION: 1pt padding, 1.0 line-height */
  .problem-card {
    border: none !important;
    padding: 1pt 0 !important;
    margin: 0;
    line-height: 1.0 !important;
    page-break-inside: avoid;
    background: white !important;
    box-shadow: none !important;
    transform: none !important;
  }

  .problem-number {
    display: none;
  }

  .problem-content {
    padding: 0;
    margin: 0;
  }

  /* Problem layout - vertically centered */
  .problem {
    display: flex;
    justify-content: center;
    align-items: center;  /* Vertical centering */
    gap: 6pt;
    font-size: 11pt;
    font-family: "Times New Roman", serif;
    line-height: 1.2;
    min-height: 16pt;  /* Consistent row height */
  }

  .problem-horizontal {
    gap: 5pt;
  }

  /* Operands - vertically centered */
  .operand {
    min-width: 20pt;
    display: inline-flex;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 0 2pt;
    vertical-align: middle;
  }

  /* Operator - vertically centered */
  .operator {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0 3pt;
    color: #000;
    font-weight: bold;
    font-size: 11pt;
    vertical-align: middle;
    line-height: 1;
  }

  /* Equals sign - vertically centered */
  .equals {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0 3pt;
    color: #000;
    font-size: 11pt;
    vertical-align: middle;
    line-height: 1;
  }

  /* Answer blank - push down to baseline level */
  .answer-blank {
    display: inline-block;
    min-width: 28pt;
    border-bottom: 1pt solid #000;
    padding: 0 4pt;
    text-align: center;
    margin-left: 2pt;
    /* Push answer line down to baseline in print */
    transform: translateY(6px);
  }
}

/* ==========================================================================
   V7 BEAUTIFIED HEADER
   ========================================================================== */

.header-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: var(--ui-page-max-width);
  margin: 0 auto;
  width: 100%;
  padding: 0 clamp(16px, 4vw, 32px);
}

.site-logo {
  display: flex;
  align-items: center;
  gap: var(--ui-gap-sm);
  text-decoration: none;
  color: var(--ui-text);
  transition: opacity var(--ui-transition-fast);
}

.site-logo:hover {
  opacity: 0.8;
}

.logo-icon {
  width: var(--ui-icon-xl);
  height: var(--ui-icon-xl);
  flex-shrink: 0;
}

.logo-text {
  font-size: var(--ui-text-h4);
  font-weight: var(--ui-weight-bold);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--ui-gap-md);
}

/* Header Navigation - Center navigation links */
.header-nav {
  display: flex;
  align-items: center;
  gap: var(--ui-gap-xs);
}

.header-nav .nav-link {
  padding: var(--ui-padding-xs) var(--ui-padding-sm);
  font-size: var(--ui-text-small);
  border-bottom: none;
}

.header-nav .nav-link:hover {
  background: var(--ui-state-hover-bg);
  border-radius: var(--ui-radius-sm);
}

.header-nav .nav-link.active {
  background: var(--ui-state-selected-bg);
  border-radius: var(--ui-radius-sm);
  color: var(--ui-link);
}

/* ==========================================================================
   V7 THEME SWITCHER DOTS
   ========================================================================== */

.theme-switcher {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 0;
  margin: 0;
  background: none;
}

.theme-dot {
  width: var(--ui-icon-sm);
  height: 14px;
  border-radius: 50%;
  border: 1.5px solid var(--ui-border-muted);
  background: var(--dot-color, var(--ui-bg-muted));
  cursor: pointer;
  padding: 0;
  transition: transform var(--ui-transition-fast),
              border-color var(--ui-transition-fast),
              box-shadow var(--ui-transition-fast);
}

.theme-dot:hover {
  transform: scale(1.2);
  border-color: var(--ui-border-hover);
}

.theme-dot:focus {
  outline: none;
  box-shadow: 0 0 0 1px var(--ui-bg), 0 0 0 2px var(--ui-link);
}

.theme-dot[aria-checked="true"],
.theme-dot.active {
  border-color: var(--ui-link);
  box-shadow: 0 0 0 1px var(--ui-bg), 0 0 0 2px var(--ui-link);
  transform: scale(1.15);
}

/* ==========================================================================
   V7 LANGUAGE SELECTOR BUTTON
   ========================================================================== */

.language-btn {
  display: flex;
  align-items: center;
  gap: var(--ui-gap-xs);
  padding: var(--ui-padding-xs) var(--ui-padding-sm);
  background: var(--ui-bg-subtle);
  border: 1px solid var(--ui-border-muted);
  border-radius: var(--ui-radius-md);
  cursor: pointer;
  font-family: inherit;
  font-size: var(--ui-text-small);
  color: var(--ui-text);
  transition: background var(--ui-transition-fast),
              border-color var(--ui-transition-fast);
}

.language-btn:hover {
  background: var(--ui-state-hover-bg);
  border-color: var(--ui-border-hover);
}

.lang-icon {
  font-size: 1rem;
}

.lang-flag {
  font-size: 1.25em;
  line-height: 1;
  margin-right: 4px;
}

.lang-code {
  font-weight: var(--ui-weight-medium);
  text-transform: uppercase;
}

/* Flag in dropdown options */
.language-option .lang-flag {
  font-size: 1.1em;
  margin-right: 6px;
  vertical-align: middle;
}

.lang-arrow {
  font-size: 0.75rem;
  opacity: 0.6;
}

/* ==========================================================================
   V7 MAIN NAVIGATION
   ========================================================================== */

.main-nav {
  background: var(--ui-bg-subtle);
  border-bottom: 1px solid var(--ui-border-muted);
}

.nav-container {
  display: flex;
  align-items: center;
  gap: var(--ui-gap-xs);
  max-width: var(--ui-page-max-width);
  margin: 0 auto;
  padding: 0 clamp(16px, 4vw, 32px);
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.nav-link {
  display: flex;
  align-items: center;
  gap: var(--ui-gap-xs);
  padding: var(--ui-padding-sm) var(--ui-padding-md);
  color: var(--ui-text-muted);
  text-decoration: none;
  font-size: var(--ui-text-small);
  font-weight: var(--ui-weight-medium);
  white-space: nowrap;
  border-bottom: 2px solid transparent;
  transition: color var(--ui-transition-fast),
              border-color var(--ui-transition-fast);
}

.nav-link:hover {
  color: var(--ui-text);
  border-bottom-color: var(--ui-border-hover);
}

.nav-link.active {
  color: var(--ui-link);
  border-bottom-color: var(--ui-link);
}

.nav-icon {
  font-size: 1rem;
}

/* Nav Categories - Left side category links */
.nav-categories {
  display: flex;
  align-items: center;
  gap: var(--ui-gap-xs);
}

/* ==========================================================================
   BREADCRUMB NAVIGATION - V7 Standard Component
   面包屑导航 - 所有站点必须使用此标准组件
   ========================================================================== */

/* 外层容器：固定高度 4rem，垂直居中 */
.breadcrumb-bar {
  height: 4rem;
  display: flex;
  align-items: center;
  background: transparent;
  border: none;
  border-bottom: 1px solid var(--ui-border-muted);
}

/* Sudoku 站点：移除面包屑边框和背景 */
[data-site="sudoku"] .breadcrumb-bar {
  border-bottom: none;
  background: none;
}

/* 隐藏空的面包屑栏 */
.breadcrumb-bar:empty,
.breadcrumb-bar:not(:has(.nav-breadcrumbs)) {
  display: none;
}

/* 内部容器继承 v7-container 的 max-width */
.breadcrumb-bar > .v7-container {
  width: 100%;
}

/* 面包屑导航链接组 */
.nav-breadcrumbs {
  display: flex;
  align-items: center;
  height: 100%;
  gap: 0.5rem;
  font-size: 0.875rem;
  color: var(--ui-text-muted);
}

/* 面包屑链接 */
.breadcrumb-link {
  color: var(--ui-text-muted);
  text-decoration: none;
  transition: color 0.15s ease;
}

.breadcrumb-link:hover {
  color: var(--ui-link);
}

/* 分隔符 */
.breadcrumb-sep {
  color: var(--ui-border);
  padding: 0 0.25rem;
}

/* 当前页面 */
.breadcrumb-current {
  color: var(--ui-text);
  font-weight: 500;
}

/* ==========================================================================
   V7 FOOTER
   ========================================================================== */

.site-footer {
  background: var(--ui-bg-muted);
  border-top: 1px solid var(--ui-border-muted);
  padding: var(--ui-padding-lg);
  margin-top: auto;
}

.footer-container {
  max-width: var(--ui-page-max-width);
  margin: 0 auto;
  padding: 0 clamp(16px, 4vw, 32px);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--ui-gap-md);
}

.footer-links {
  display: flex;
  align-items: center;
  gap: var(--ui-gap-md);
  flex-wrap: wrap;
  justify-content: center;
}

.footer-links a {
  color: var(--ui-text-muted);
  font-size: var(--ui-text-small);
  text-decoration: none;
  transition: color var(--ui-transition-fast);
}

.footer-links a:hover {
  color: var(--ui-link);
}

.footer-divider {
  color: var(--ui-text-subtle);
}

.footer-copyright {
  color: var(--ui-text-subtle);
  font-size: var(--ui-text-tiny);
  text-align: center;
}

/* ==========================================================================
   V7 HERO SECTION
   ========================================================================== */

.hero-section {
  text-align: center;
  padding: var(--ui-section-gap) var(--ui-padding-lg);
  background: linear-gradient(180deg, var(--ui-bg-muted) 0%, var(--ui-bg) 100%);
  border-radius: var(--ui-radius-lg);
  margin-bottom: var(--ui-section-gap);
}

.hero-title {
  font-size: clamp(1.75rem, 5vw, 2.5rem);
  font-weight: var(--ui-weight-bold);
  color: var(--ui-text);
  margin-bottom: var(--ui-gap-md);
}

.hero-subtitle {
  font-size: var(--ui-text-large);
  color: var(--ui-text-muted);
  max-width: var(--ui-container-sm);
  margin: 0 auto;
}

/* ==========================================================================
   V7 TOPIC CARDS (Home Page)
   ========================================================================== */

.topics-section {
  margin-bottom: var(--ui-section-gap);
}

.section-title {
  font-size: var(--ui-text-h3);
  font-weight: var(--ui-weight-bold);
  color: var(--ui-text);
  margin-bottom: var(--ui-gap-lg);
}

.topic-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  gap: var(--ui-gap-md);
}

.topic-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--ui-gap-sm);
  padding: var(--ui-padding-lg);
  background: var(--ui-bg);
  border: 1px solid var(--ui-border);
  border-radius: var(--ui-radius-md);  /* Uses site-specific radius */
  box-shadow: var(--ui-shadow-card);   /* Uses site-specific shadow */
  text-decoration: none;
  text-align: center;
  transition: border-color var(--ui-transition-fast),
              box-shadow var(--ui-transition-fast),
              transform var(--ui-transition-fast);
}

.topic-card:hover {
  border-color: var(--site-primary, var(--ui-link));
  box-shadow: var(--ui-shadow-card-hover);  /* Uses site-specific hover shadow */
  transform: translateY(-3px);
}

.topic-icon {
  font-size: 2rem;
  line-height: 1;
}

.topic-name {
  font-weight: var(--ui-weight-semibold);
  color: var(--ui-text);
  font-size: var(--ui-text-body);
}

.topic-card:hover .topic-name {
  color: var(--ui-link);
}

.topic-count {
  font-size: var(--ui-text-tiny);
  color: var(--ui-text-muted);
}

/* ==========================================================================
   V7 FEATURED SECTION (Home Page)
   ========================================================================== */

.featured-section {
  margin-bottom: var(--ui-section-gap);
}

.featured-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--ui-gap-md);
}

.featured-card {
  display: block;
  padding: var(--ui-padding-lg);
  background: var(--ui-bg);
  border: 1px solid var(--ui-border-muted);
  border-radius: var(--ui-radius-lg);
  text-decoration: none;
  transition: border-color var(--ui-transition-fast),
              box-shadow var(--ui-transition-fast);
}

.featured-card:hover {
  border-color: var(--ui-link);
  box-shadow: var(--ui-shadow-md);
}

.featured-badge {
  display: inline-block;
  font-size: var(--ui-text-tiny);
  color: var(--ui-text-muted);
  margin-bottom: var(--ui-gap-sm);
}

.featured-title {
  font-size: var(--ui-text-large);
  font-weight: var(--ui-weight-semibold);
  color: var(--ui-text);
  margin: 0 0 var(--ui-gap-xs);
}

.featured-card:hover .featured-title {
  color: var(--ui-link);
}

.featured-excerpt {
  font-size: var(--ui-text-small);
  color: var(--ui-text-muted);
  margin: 0;
}

/* ==========================================================================
   V7 TAG GRID (Secondary Dimensions)
   ========================================================================== */

.tag-grid {
  display: flex;
  flex-wrap: wrap;
  gap: var(--ui-gap-sm);
}

.tag-link {
  display: inline-block;
  padding: var(--ui-padding-xs) var(--ui-padding-md);
  background: var(--ui-bg-subtle);
  border: 1px solid var(--ui-border-muted);
  border-radius: var(--ui-radius-full);
  font-size: var(--ui-text-small);
  color: var(--ui-text);
  text-decoration: none;
  transition: background var(--ui-transition-fast),
              border-color var(--ui-transition-fast),
              color var(--ui-transition-fast);
}

.tag-link:hover {
  background: var(--ui-bg-accent);
  border-color: var(--ui-link);
  color: var(--ui-link);
}

/* ==========================================================================
   V7 PAGE HEADER (Category, Content Pages)
   ========================================================================== */

.page-header {
  margin-bottom: var(--ui-gap-lg);
}

.page-title {
  font-size: var(--ui-text-h2);
  font-weight: var(--ui-weight-bold);
  color: var(--ui-text);
  margin-bottom: var(--ui-gap-sm);
}

.page-description {
  font-size: var(--ui-text-body);
  color: var(--ui-text-muted);
  margin: 0;
}

.page-meta {
  font-size: var(--ui-text-small);
  color: var(--ui-text-subtle);
  margin: 0;
}

/* ==========================================================================
   V7 SIBLING NAVIGATION (Category Page)
   ========================================================================== */

.sibling-nav {
  margin-bottom: 1.5rem;
}

.sibling-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  padding: var(--ui-padding-sm);
  background: var(--ui-bg-muted);
  border-radius: var(--ui-radius-lg);
}

.sibling-tab {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.625rem 1rem;
  background: transparent;
  border: 1px solid var(--ui-border-muted);
  border-radius: 8px;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--ui-text-muted);
  text-decoration: none;
  transition: border-color 0.2s ease, color 0.2s ease;
}

.sibling-tab .icon {
  width: var(--ui-icon-md);
  height: 16px;
  opacity: 0.6;
}

.sibling-tab:hover {
  border-color: var(--ui-link);
  color: var(--ui-link);
}

.sibling-tab:hover .icon {
  opacity: 1;
}

.sibling-tab.active {
  background: var(--ui-link);
  border-color: var(--ui-link);
  color: white;
}

.sibling-tab.active .icon {
  opacity: 1;
}

/* ==========================================================================
   V7 PREMIUM - CONTENT CARDS (Category Page Worksheets)
   ========================================================================== */

.content-section {
  margin-bottom: 1.5rem;
}

.content-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.content-card {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1.25rem 1.5rem;
  background: var(--ui-bg);
  border: 1px solid var(--ui-border-muted);
  border-radius: 10px;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.content-card:hover {
  border-color: var(--ui-link);
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.06);
}

.content-card-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.content-card-icon .icon {
  width: var(--ui-icon-lg);
  height: 24px;
  color: var(--ui-text);
  opacity: 0.4;
}

.content-card-body {
  flex: 1;
  min-width: 0;
}

.content-card-title {
  font-size: 1rem;
  font-weight: 600;
  margin: 0 0 0.25rem;
  line-height: 1.4;
}

.content-card-title a {
  color: var(--ui-text);
  text-decoration: none;
}

.content-card:hover .content-card-title a {
  color: var(--ui-text);
}

.content-card-excerpt {
  font-size: 0.9375rem;
  color: var(--ui-text-muted);
  margin: 0;
  line-height: 1.5;
}

.content-card-action {
  display: flex;
  align-items: center;
  gap: 0.375rem;
  flex-shrink: 0;
  font-size: 0.875rem;
  color: var(--ui-link);
  text-decoration: none;
  font-weight: 500;
  transition: color 0.2s ease;
}

.content-card:hover .content-card-action {
  color: var(--ui-link-hover);
}

.content-card-action .icon {
  width: var(--ui-icon-sm);
  height: 14px;
  transition: transform 0.2s ease;
}

.content-card:hover .content-card-action .icon {
  transform: translateX(3px);
}

/* ==========================================================================
   V7 SUBCATEGORY GRID (Category Page)
   ========================================================================== */

.subcategories-section {
  margin-bottom: var(--ui-section-gap);
}

.subcategory-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: var(--ui-gap-md);
}

.subcategory-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--ui-padding-md);
  background: var(--ui-bg-subtle);
  border: 1px solid var(--ui-border-muted);
  border-radius: var(--ui-radius-md);
  text-decoration: none;
  transition: all var(--ui-transition-fast);
}

.subcategory-card:hover {
  background: var(--ui-bg);
  border-color: var(--ui-link);
}

.subcategory-name {
  font-weight: var(--ui-weight-medium);
  color: var(--ui-text);
}

.subcategory-card:hover .subcategory-name {
  color: var(--ui-link);
}

.subcategory-count {
  font-size: var(--ui-text-tiny);
  color: var(--ui-text-subtle);
  background: var(--ui-bg-muted);
  padding: 2px 8px;
  border-radius: var(--ui-radius-full);
}

/* ==========================================================================
   V7 EMPTY STATE
   ========================================================================== */

.empty-section {
  text-align: center;
  padding: var(--ui-section-gap) var(--ui-padding-lg);
}

.empty-icon {
  font-size: 3rem;
  margin-bottom: var(--ui-gap-md);
  opacity: 0.5;
}

.empty-title {
  font-size: var(--ui-text-h4);
  font-weight: var(--ui-weight-semibold);
  color: var(--ui-text);
  margin-bottom: var(--ui-gap-sm);
}

.empty-text {
  font-size: var(--ui-text-body);
  color: var(--ui-text-muted);
  margin-bottom: var(--ui-gap-lg);
}

.empty-link {
  color: var(--ui-link);
}

/* ==========================================================================
   V7 LEGAL PAGES (Privacy, Terms)
   ========================================================================== */

.legal-page {
  max-width: var(--ui-container-md);
  margin: 0 auto;
}

.legal-content {
  line-height: 1.7;
}

.legal-section {
  margin-bottom: var(--ui-gap-xl);
}

.legal-section h2 {
  font-size: var(--ui-text-h4);
  font-weight: var(--ui-weight-semibold);
  color: var(--ui-text);
  margin-bottom: var(--ui-gap-md);
  padding-bottom: var(--ui-gap-sm);
  border-bottom: 1px solid var(--ui-border-muted);
}

.legal-section p {
  color: var(--ui-text-muted);
  margin-bottom: var(--ui-gap-md);
}

.legal-section ul {
  margin: var(--ui-gap-md) 0;
  padding-left: var(--ui-padding-lg);
  color: var(--ui-text-muted);
}

.legal-section li {
  margin-bottom: var(--ui-gap-sm);
}

/* Link List - used for navigation lists like 404 page */
.link-list {
  list-style: disc;
  margin-left: var(--ui-gap-xl);
  line-height: 2;
}

.link-list a {
  color: var(--ui-link);
  text-decoration: underline;
}

.link-list a:hover {
  color: var(--ui-link-hover);
}

.legal-footer {
  margin-top: var(--ui-section-gap);
  padding-top: var(--ui-gap-lg);
  border-top: 1px solid var(--ui-border-muted);
}

.back-link {
  color: var(--ui-link);
  font-weight: var(--ui-weight-medium);
}

/* ==========================================================================
   V7 RESPONSIVE ADJUSTMENTS
   ========================================================================== */

@media (max-width: 768px) {
  .header-container {
    flex-wrap: wrap;
    gap: var(--ui-gap-sm);
  }

  .header-actions {
    gap: var(--ui-gap-sm);
  }

  .theme-dot {
    width: var(--ui-icon-md);
    height: 16px;
  }

  .nav-container {
    padding: 0 var(--ui-padding-md);
  }

  .nav-link {
    padding: var(--ui-padding-xs) var(--ui-padding-sm);
    font-size: var(--ui-text-tiny);
  }

  .hero-section {
    padding: var(--ui-gap-xl) var(--ui-padding-md);
  }

  .topic-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .topic-card {
    padding: var(--ui-padding-md);
  }

  .topic-icon {
    font-size: 1.5rem;
  }

  .featured-grid {
    grid-template-columns: 1fr;
  }

  .sibling-tabs {
    overflow-x: auto;
    flex-wrap: nowrap;
    -webkit-overflow-scrolling: touch;
  }

  .sibling-tab {
    flex-shrink: 0;
  }

  .content-card {
    flex-direction: column;
    align-items: flex-start;
    text-align: left;
  }

  .content-card-action {
    align-self: flex-end;
    margin-top: var(--ui-gap-sm);
  }

  .footer-container {
    text-align: center;
  }

  .footer-links {
    flex-direction: column;
    gap: var(--ui-gap-sm);
  }

  .footer-divider {
    display: none;
  }
}

@media (max-width: 480px) {
  .logo-text {
    display: none;
  }

  .topic-grid {
    grid-template-columns: 1fr 1fr;
    gap: var(--ui-gap-sm);
  }

  .topic-card {
    padding: var(--ui-padding-sm);
  }

  .topic-icon {
    font-size: 1.25rem;
  }

  .topic-name {
    font-size: var(--ui-text-small);
  }

  .subcategory-grid {
    grid-template-columns: 1fr;
  }
}

/* ==========================================================================
   V7 PRINT OVERRIDES FOR NEW COMPONENTS
   ========================================================================== */

/* Print-only header (hidden on screen, visible in print) */
.print-header {
  display: none;
}

@media print {
  /* Hide web header, navigation, and action buttons entirely */
  .site-header,
  .main-nav,
  .site-footer,
  .theme-switcher,
  .language-switcher,
  .sibling-nav,
  .hero-section,
  .header-actions,
  .header-nav,
  .action-buttons {
    display: none !important;
  }

  /* Show print-only header - STACKED layout to prevent title overlap */
  .print-header {
    display: block !important;
    margin: 0 0 8pt 0;
    padding: 0;
    border-bottom: 1.5pt solid #000;
    padding-bottom: 6pt;
  }

  /* Print title - first line, left aligned */
  .print-title {
    font-size: 13pt;
    font-weight: bold;
    color: #000;
    margin: 0 0 2pt 0;
    padding: 0;
    text-align: left;
    line-height: 1.2;
  }

  /* Print meta (Name/Date) - second line, right aligned */
  .print-meta {
    display: flex;
    justify-content: flex-end;
    gap: 12pt;
    font-size: 9pt;
    color: #000;
    margin: 0;
  }

  .print-field {
    display: inline-flex;
    align-items: baseline;
    gap: 3pt;
  }

  .print-line {
    display: inline-block;
    width: 60pt;
    border-bottom: 0.75pt solid #000;
    vertical-align: baseline;
  }

  .legal-page {
    max-width: 100%;
  }

  .legal-section h2 {
    page-break-after: avoid;
  }

  .legal-section {
    page-break-inside: avoid;
  }
}

/* ==========================================================================
   V7 BEAUTIFICATION - ICON SYSTEM
   ========================================================================== */

.icon {
  width: 1em;
  height: 1em;
  vertical-align: -0.125em;
  fill: currentColor;
  stroke: currentColor;
  flex-shrink: 0;
}

.section-icon {
  width: 1.25em;
  height: 1.25em;
  margin-right: 0.5rem;
  opacity: 0.8;
}

/* ==========================================================================
   V7 PREMIUM HERO SECTION - Clean & Bold
   ========================================================================== */

.hero-section {
  text-align: center;
  padding: 6rem 2rem 5rem;
  margin-bottom: 4rem;
}

.hero-title {
  font-size: clamp(3rem, 8vw, 5rem);
  font-weight: 700;
  color: var(--ui-text);
  margin: 0 0 1.5rem;
  letter-spacing: -0.03em;
  line-height: 1.1;
}

.hero-subtitle {
  font-size: clamp(1.125rem, 2vw, 1.375rem);
  color: var(--ui-text-muted);
  max-width: var(--ui-container-sm);
  margin: 0 auto;
  line-height: 1.6;
  font-weight: 400;
}

/* ==========================================================================
   V7 VALUE PROPS - Minimal Stats Bar
   ========================================================================== */

.value-section {
  padding: 2rem 1.5rem;
  margin-top: 2rem;
  border-top: 1px solid var(--ui-border-muted);
}

.value-grid {
  display: flex;
  justify-content: center;
  gap: 5rem;
}

.value-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
}

.value-number {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--ui-text);
  letter-spacing: -0.02em;
}

.value-label {
  font-size: 0.875rem;
  color: var(--ui-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* ==========================================================================
   V7 PREMIUM SECTION HEADERS
   ========================================================================== */

.section-header {
  margin-bottom: 1.25rem;
}

.section-title {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--ui-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin: 0 0 0.75rem;
}

.section-subtitle {
  font-size: var(--ui-text-body);
  color: var(--ui-text-muted);
  margin: 0;
}

/* Home page section title - centered */
.topics-section .section-title {
  text-align: center;
  margin-bottom: 3rem;
}

/* ==========================================================================
   V7 PREMIUM TOPIC CARDS - Clean & Spacious
   ========================================================================== */

.topics-section {
  padding: 0 2rem;
}

.topic-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1.5rem;
  max-width: var(--ui-container-md);
  margin: 0 auto;
}

.topic-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.25rem;
  padding: 2.5rem 2rem;
  background: var(--ui-bg);
  border: 1px solid var(--ui-border-muted);
  border-radius: 12px;
  text-decoration: none;
  text-align: center;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.topic-card:hover {
  border-color: var(--ui-link);
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
}

.topic-icon-wrapper {
  display: flex;
  align-items: center;
  justify-content: center;
  width: var(--ui-icon-4xl);
  height: 56px;
}

.topic-icon {
  width: var(--ui-icon-2xl);
  height: 40px;
  color: var(--ui-text);
  opacity: 0.7;
  transition: opacity 0.2s ease;
}

.topic-card:hover .topic-icon {
  opacity: 1;
  color: var(--ui-link);
}

.topic-name {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--ui-text);
  letter-spacing: -0.01em;
}

/* ==========================================================================
   V7 BEAUTIFICATION - FEATURED CARDS
   ========================================================================== */

.featured-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1rem;
}

.featured-card {
  display: flex;
  flex-direction: column;
  padding: 1.5rem;
  background: var(--ui-bg);
  border: 1px solid var(--ui-border-muted);
  border-radius: var(--ui-radius-lg);
  text-decoration: none;
  transition: all 0.2s ease;
}

.featured-card:hover {
  border-color: var(--ui-link);
  box-shadow: var(--ui-shadow-md);
  transform: translateY(-2px);
}

.featured-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.375rem;
  font-size: var(--ui-text-tiny);
  color: var(--ui-text-muted);
  margin-bottom: 0.75rem;
}

.featured-badge .icon {
  width: var(--ui-icon-sm);
  height: 14px;
  color: var(--ui-warning);
}

.featured-title {
  font-size: var(--ui-text-large);
  font-weight: var(--ui-weight-semibold);
  color: var(--ui-text);
  margin: 0 0 0.5rem;
  transition: color 0.2s ease;
}

.featured-card:hover .featured-title {
  color: var(--ui-link);
}

.featured-excerpt {
  font-size: var(--ui-text-small);
  color: var(--ui-text-muted);
  margin: 0 0 1rem;
  flex-grow: 1;
}

.featured-action {
  display: flex;
  align-items: center;
  gap: 0.375rem;
  font-size: var(--ui-text-small);
  font-weight: var(--ui-weight-medium);
  color: var(--ui-link);
}

.featured-action .icon {
  width: var(--ui-icon-sm);
  height: 14px;
  transition: transform 0.2s ease;
}

.featured-card:hover .featured-action .icon {
  transform: translateX(4px);
}

/* ==========================================================================
   V7 BEAUTIFICATION - HOW IT WORKS SECTION
   ========================================================================== */

.how-it-works-section {
  margin-top: 3rem;
  margin-bottom: 2rem;
  padding: 2rem;
  background: var(--ui-bg-muted);
  border-radius: var(--ui-radius-xl);
}

.how-it-works-section .section-header {
  text-align: center;
}

.steps-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem;
  margin-top: 1.5rem;
}

.step-card {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: 2rem 1.5rem;
  background: var(--ui-bg);
  border-radius: var(--ui-radius-lg);
  box-shadow: var(--ui-shadow-sm);
}

.step-number {
  position: absolute;
  top: -12px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  align-items: center;
  justify-content: center;
  width: var(--ui-icon-xl);
  height: 28px;
  background: var(--ui-link);
  color: white;
  font-size: var(--ui-text-small);
  font-weight: var(--ui-weight-bold);
  border-radius: 50%;
}

.step-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: var(--ui-icon-4xl);
  height: 56px;
  background: var(--ui-bg-subtle);
  border-radius: 50%;
  margin-bottom: 1rem;
}

.step-icon .icon {
  width: var(--ui-icon-xl);
  height: 28px;
  color: var(--ui-link);
}

.step-title {
  font-size: var(--ui-text-body);
  font-weight: var(--ui-weight-semibold);
  color: var(--ui-text);
  margin: 0 0 0.5rem;
}

.step-description {
  font-size: var(--ui-text-small);
  color: var(--ui-text-muted);
  margin: 0;
  line-height: 1.5;
}

/* ==========================================================================
   V7 PREMIUM - CATEGORY HEADER (Clean & Spacious)
   ========================================================================== */

.category-page {
  padding: 3rem 2rem;
  max-width: var(--ui-page-max-width);
  margin: 0 auto;
}

.category-header {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  margin-bottom: 3rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--ui-border-muted);
}

.category-icon-wrapper {
  display: flex;
  align-items: center;
  justify-content: center;
  width: var(--ui-icon-5xl);
  height: 64px;
  flex-shrink: 0;
}

.category-icon {
  width: var(--ui-icon-3xl);
  height: 48px;
  color: var(--ui-text);
  opacity: 0.7;
}

.category-header-content {
  flex-grow: 1;
}

.category-header .page-title {
  font-size: clamp(2rem, 5vw, 2.75rem);
  font-weight: 700;
  color: var(--ui-text);
  letter-spacing: -0.02em;
  margin: 0 0 0.5rem;
  line-height: 1.2;
}

.category-header .page-description {
  font-size: 1.125rem;
  color: var(--ui-text-muted);
  margin: 0;
  line-height: 1.6;
}

/* ==========================================================================
   V7 PREMIUM - SUBCATEGORY CARDS (Clean & Spacious)
   ========================================================================== */

.subcategories-section {
  margin-bottom: 3rem;
}

.subcategories-section .section-header {
  margin-bottom: 2rem;
}

.subcategories-section .section-subtitle {
  margin-top: 0.5rem;
}

.subcategory-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.25rem;
}

.subcategory-card {
  display: flex;
  flex-direction: column;
  padding: 1.75rem;
  background: var(--ui-bg);
  border: 1px solid var(--ui-border);
  border-radius: var(--ui-radius-md);  /* Site-specific radius */
  box-shadow: var(--ui-shadow-card);   /* Site-specific shadow */
  text-decoration: none;
  transition: border-color 0.2s ease, box-shadow 0.2s ease, transform 0.2s ease;
}

.subcategory-card:hover {
  border-color: var(--site-primary, var(--ui-link));
  box-shadow: var(--ui-shadow-card-hover);  /* Site-specific hover shadow */
  transform: translateY(-2px);
}

.subcategory-card-header {
  display: flex;
  align-items: center;
  gap: 0.875rem;
  margin-bottom: 0.875rem;
}

.subcategory-icon {
  width: var(--ui-icon-lg);
  height: 24px;
  color: var(--ui-text);
  opacity: 0.5;
  flex-shrink: 0;
}

.subcategory-name {
  font-weight: 600;
  color: var(--ui-text);
  font-size: 1.0625rem;
  letter-spacing: -0.01em;
}

.subcategory-description {
  font-size: 0.9375rem;
  color: var(--ui-text-muted);
  margin: 0 0 1.25rem;
  line-height: 1.6;
  flex-grow: 1;
}

.subcategory-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 1rem;
  border-top: 1px solid var(--ui-border-muted);
}

.subcategory-count {
  font-size: 0.8125rem;
  color: var(--ui-text-muted);
}

.subcategory-action {
  display: flex;
  align-items: center;
  gap: 0.375rem;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--ui-link);
  transition: color 0.2s ease;
}

.subcategory-card:hover .subcategory-action {
  color: var(--ui-link-hover);
}

.subcategory-action .icon {
  width: var(--ui-icon-sm);
  height: 14px;
  transition: transform 0.2s ease;
}

.subcategory-card:hover .subcategory-action .icon {
  transform: translateX(3px);
}

/* ==========================================================================
   V7 PREMIUM - WORKSHEET HEADER (CONTENT PAGE)
   ========================================================================== */

.content-page {
  padding: 2rem;
  max-width: var(--ui-page-max-width);
  margin: 0 auto;
}

.worksheet-article {
  max-width: 100%;
}

.worksheet-header {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  margin-bottom: 2rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--ui-border-muted);
}

.worksheet-icon-wrapper {
  display: flex;
  align-items: center;
  justify-content: center;
  width: var(--ui-icon-4xl);
  height: 56px;
  flex-shrink: 0;
}

.worksheet-icon {
  width: var(--ui-icon-2xl);
  height: 40px;
  color: var(--ui-text);
  opacity: 0.6;
}

.worksheet-header-content h1 {
  font-size: clamp(1.75rem, 4vw, 2.25rem);
  font-weight: 700;
  color: var(--ui-text);
  letter-spacing: -0.02em;
  margin: 0 0 0.5rem;
  line-height: 1.2;
}

.worksheet-description {
  font-size: 1rem;
  color: var(--ui-text-muted);
  margin: 0;
  line-height: 1.6;
}

/* ==========================================================================
   V7 PREMIUM - ACTION BUTTONS (Clean & Subtle)
   ========================================================================== */

.action-buttons {
  display: flex;
  gap: 0.75rem;
  margin-bottom: 2rem;
  flex-wrap: wrap;
}

.action-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.25rem;
  font-size: 0.9375rem;
  font-weight: 500;
  text-decoration: none;
  border-radius: var(--ui-radius-btn, 8px);  /* Site-specific button radius */
  border: 1px solid var(--ui-border);
  background: var(--ui-bg);
  color: var(--ui-text);
  cursor: pointer;
  transition: border-color 0.2s ease, box-shadow 0.2s ease, transform 0.15s ease;
}

.action-btn .icon {
  width: calc(var(--ui-icon-md) + 2px);
  height: 18px;
  opacity: 0.7;
}

.action-btn:hover {
  border-color: var(--ui-link);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
}

.action-btn.primary {
  background: var(--ui-link);
  color: white;
  border-color: var(--ui-link);
}

.action-btn.primary .icon {
  opacity: 1;
}

.action-btn.primary:hover {
  background: var(--ui-link-hover);
  border-color: var(--ui-link-hover);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.action-btn.secondary {
  background: var(--ui-bg);
  color: var(--ui-text);
  border: 1px solid var(--ui-border-muted);
}

.action-btn.secondary:hover {
  border-color: var(--ui-link);
  color: var(--ui-link);
}

.action-btn.outline {
  background: transparent;
  color: var(--ui-link);
  border: 1.5px solid var(--ui-link);
}

.action-btn.outline:hover {
  background: var(--ui-link);
  color: white;
  box-shadow: 0 2px 8px rgba(0, 102, 204, 0.25);
}

/* ==========================================================================
   V7 PREMIUM - SET SWITCHER (Clean & Minimal)
   ========================================================================== */

.set-switcher {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 2rem;
  padding: 1rem 1.25rem;
  background: transparent;
  border: 1px solid var(--ui-border-muted);
  border-radius: 10px;
  flex-wrap: wrap;
}

.set-switcher-label {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--ui-text-muted);
}

.set-switcher-label .icon {
  width: var(--ui-icon-md);
  height: 16px;
  opacity: 0.6;
}

.set-buttons {
  display: flex;
  gap: 0.25rem;
}

.set-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: calc(var(--ui-icon-xl-plus) + 2px);
  height: 34px;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--ui-text-muted);
  background: transparent;
  border: 1px solid transparent;
  border-radius: 6px;
  text-decoration: none;
  transition: all 0.15s ease;
}

.set-btn:hover {
  background: var(--ui-bg-muted);
  color: var(--ui-text);
}

.set-btn.current {
  background: var(--ui-link);
  color: white;
  border-color: var(--ui-link);
}

/* ==========================================================================
   V7 PREMIUM - PROBLEM CARDS (Clean Math Grid)
   ========================================================================== */

.generated-content {
  margin-top: 2rem;
}

.generated-content .section-header {
  margin-bottom: 1.5rem;
}

.problem-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
  margin-bottom: 2rem;
  padding: 1.5rem;
  background: var(--ui-bg-muted);
  border: 1px solid var(--ui-border);
  border-radius: 12px;
}

/* 4-column layout for smaller problems on larger screens */
@media (min-width: 1200px) {
  .problem-grid.grid-4-col {
    grid-template-columns: repeat(4, 1fr);
  }
}

.problem-card {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 90px;
  padding: 1.5rem 1rem;
  background: var(--ui-bg);
  border: 2px solid var(--ui-border);
  border-radius: 10px;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.problem-card:hover {
  border-color: var(--ui-border-hover);
  box-shadow: var(--ui-shadow-md);
}

.problem-number {
  position: absolute;
  top: 10px;
  left: 10px;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--ui-text-muted);
  opacity: 0.6;
}

.problem-content {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
}

.problem {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 0.85em;
  font-size: 1.375rem;
  font-weight: 600;
  color: var(--ui-text);
  font-family: "SF Mono", Monaco, "Cascadia Code", monospace;
  letter-spacing: 0.05em;
}

/* ==========================================================================
   V7 PREMIUM - ANSWER KEY (Clean & Subtle)
   ========================================================================== */

.answer-key {
  margin-top: 2rem;
  border: 1px solid var(--ui-border-muted);
  border-radius: 10px;
  overflow: hidden;
}

.answer-key summary {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 1rem 1.25rem;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--ui-text-muted);
  background: transparent;
  cursor: pointer;
  user-select: none;
  transition: color 0.2s ease;
}

.answer-key summary .icon {
  width: var(--ui-icon-md);
  height: 16px;
  opacity: 0.6;
}

.answer-key summary:hover {
  color: var(--ui-text);
}

.answer-key[open] summary {
  border-bottom: 1px solid var(--ui-border-muted);
  color: var(--ui-text);
}

.answer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
  gap: 0.75rem;
  padding: 1.25rem;
}

.answer-item {
  display: flex;
  align-items: baseline;
  gap: 0.5rem;
  font-size: var(--ui-text-body);
}

.answer-number {
  font-weight: var(--ui-weight-medium);
  color: var(--ui-text-muted);
}

.answer-value {
  font-weight: var(--ui-weight-semibold);
  color: var(--ui-success);
  font-family: "SF Mono", Monaco, monospace;
}

/* ==========================================================================
   SUDOKU ANSWER KEY - Compact Layout
   ========================================================================== */

[data-site="sudoku"] .answer-key {
  margin-top: 1.5rem;
  background: var(--ui-bg-muted);
}

[data-site="sudoku"] .answer-key summary {
  padding: 0.75rem 1rem;
  font-size: 0.8125rem;
}

[data-site="sudoku"] .answer-grid {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 1.5rem;
  padding: 1rem;
}

[data-site="sudoku"] .answer-item {
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
}

[data-site="sudoku"] .answer-number {
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.25rem 0.5rem;
  background: var(--sudoku-primary, var(--ui-link));
  color: white;
  border-radius: var(--ui-radius-full);
}

/* Compact sudoku solution grids */
[data-site="sudoku"] .answer-value .sudoku-grid {
  transform: scale(0.5);
  transform-origin: top center;
  margin: 0;
  box-shadow: none;
}

[data-site="sudoku"] .answer-value {
  font-family: inherit;
  color: inherit;
}

/* Even more compact on smaller screens */
@media (max-width: 768px) {
  [data-site="sudoku"] .answer-value .sudoku-grid {
    transform: scale(0.4);
  }
}

/* Print styles for sudoku answers - see print.css for detailed rules */
@media print {
  [data-site="sudoku"] .answer-key[open] {
    page-break-before: always;
  }

  [data-site="sudoku"] .answer-grid {
    gap: 10mm;
  }

  /* Note: Specific grid size transforms are in print.css */
}

/* ==========================================================================
   V7 BEAUTIFICATION - RANDOM MODE INDICATOR
   ========================================================================== */

.random-mode-indicator {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  padding: 1rem 1.25rem;
  margin-bottom: 2rem;
  background: transparent;
  border: 1px solid var(--ui-border-muted);
  border-radius: 8px;
  font-size: 0.875rem;
  color: var(--ui-text-muted);
  line-height: 1.6;
}

.random-mode-indicator .icon {
  width: var(--ui-icon-md);
  height: 16px;
  opacity: 0.5;
  flex-shrink: 0;
  margin-top: 2px;
}

/* ==========================================================================
   V7 BEAUTIFICATION - BREADCRUMBS (Lightweight)
   ========================================================================== */

.breadcrumbs {
  margin-bottom: 1.5rem;
  padding: 0;
}

.breadcrumbs ol {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.375rem;
  list-style: none;
  padding: 0;
  margin: 0;
  font-size: 0.8125rem;
}

.breadcrumbs li {
  display: flex;
  align-items: center;
  opacity: 0.7;
}

.breadcrumbs li:not(:last-child)::after {
  content: "›";
  margin-left: 0.375rem;
  color: var(--ui-text-subtle);
  opacity: 0.5;
  font-size: 0.875rem;
}

.breadcrumbs a {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  color: var(--ui-text-subtle);
  text-decoration: none;
  transition: color 0.15s ease, opacity 0.15s ease;
}

.breadcrumbs a:hover {
  color: var(--ui-link);
  opacity: 1;
}

.breadcrumbs a .icon {
  width: var(--ui-icon-xs);
  height: 12px;
  opacity: 0.6;
}

.breadcrumbs li[aria-current="page"] {
  color: var(--ui-text-muted);
  opacity: 0.8;
  font-weight: var(--ui-weight-medium);
}

/* ==========================================================================
   V7 BEAUTIFICATION - ERROR BLOCK
   ========================================================================== */

.error-block {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
  padding: 3rem 2rem;
  text-align: center;
  background: var(--ui-bg-muted);
  border-radius: var(--ui-radius-lg);
}

.error-block .icon {
  width: var(--ui-icon-3xl);
  height: 48px;
  color: var(--ui-text-subtle);
}

.error-block p {
  margin: 0;
  color: var(--ui-text-muted);
}

/* ==========================================================================
   V7 PREMIUM RESPONSIVE ADJUSTMENTS
   ========================================================================== */

@media (max-width: 768px) {
  .hero-section {
    padding: 4rem 1.5rem 3rem;
  }

  .hero-title {
    font-size: 2.5rem;
  }

  .hero-subtitle {
    font-size: 1rem;
  }

  .topics-section {
    padding: 0 1rem;
  }

  .topic-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
  }

  .topic-card {
    padding: 1.75rem 1.25rem;
  }

  .topic-icon-wrapper {
    width: var(--ui-icon-3xl);
    height: 48px;
  }

  .topic-icon {
    width: var(--ui-icon-xl-plus);
    height: 32px;
  }

  .topic-name {
    font-size: 1rem;
  }

  .value-section {
    padding: 3rem 1.5rem;
  }

  .value-grid {
    gap: 2.5rem;
  }

  .value-number {
    font-size: 2rem;
  }

  .category-header {
    flex-direction: column;
    align-items: center;
    text-align: center;
  }

  .category-icon-wrapper {
    width: var(--ui-icon-4xl);
    height: 56px;
  }

  .category-icon {
    width: var(--ui-icon-xl);
    height: 28px;
  }

  .worksheet-header {
    flex-direction: column;
    align-items: center;
    text-align: center;
  }

  .worksheet-icon-wrapper {
    width: var(--ui-icon-4xl);
    height: 56px;
  }

  .worksheet-icon {
    width: var(--ui-icon-xl);
    height: 28px;
  }

  .action-buttons {
    justify-content: center;
  }

  .problem-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
  }
}

/* Single column on very small screens */
@media (max-width: 480px) {
  .problem-grid {
    grid-template-columns: 1fr;
  }
}

/* ==========================================================================
   LEGAL PAGES (Privacy, Terms)
   ========================================================================== */

.legal-page {
  max-width: var(--ui-container-md);
  margin: 0 auto;
  padding: var(--ui-padding-xl) var(--ui-padding-lg);
}

.legal-header {
  text-align: center;
  margin-bottom: var(--ui-section-gap);
  padding-bottom: var(--ui-gap-lg);
  border-bottom: 1px solid var(--ui-border);
}

.legal-header h1 {
  font-size: var(--ui-text-3xl);
  font-weight: var(--ui-weight-bold);
  color: var(--ui-text);
  margin-bottom: var(--ui-gap-md);
}

.legal-meta {
  font-size: var(--ui-text-small);
  color: var(--ui-text-muted);
}

.legal-content {
  line-height: 1.8;
  color: var(--ui-text);
}

.legal-section {
  margin-bottom: var(--ui-gap-xl);
}

.legal-section h2 {
  font-size: var(--ui-text-xl);
  font-weight: var(--ui-weight-semibold);
  color: var(--ui-text);
  margin-bottom: var(--ui-gap-md);
  padding-bottom: var(--ui-gap-sm);
  border-bottom: 1px solid var(--ui-border-subtle);
}

.legal-section p {
  margin-bottom: var(--ui-gap-md);
  color: var(--ui-text-secondary);
}

.legal-section ul {
  list-style: disc;
  margin-left: var(--ui-gap-xl);
  margin-bottom: var(--ui-gap-md);
}

.legal-section li {
  margin-bottom: var(--ui-gap-sm);
  color: var(--ui-text-secondary);
}

@media (max-width: 768px) {
  .legal-page {
    padding: var(--ui-padding-lg) var(--ui-padding-md);
  }

  .legal-header h1 {
    font-size: var(--ui-text-2xl);
  }

  .legal-section h2 {
    font-size: var(--ui-text-lg);
  }
}

/* ==========================================================================
   SEO INTRODUCTION CONTENT - Phase 2 Integration
   ========================================================================== */

/**
 * General SEO introduction content
 * Used on: Home, Content, Privacy, Terms, About pages
 */
.intro-content {
  margin: var(--ui-gap-2xl) 0;
  padding: var(--ui-padding-xl);
  background: linear-gradient(135deg, var(--ui-bg-subtle) 0%, var(--ui-bg) 100%);
  border-radius: var(--ui-radius-lg);
  border: 1px solid var(--ui-border);
  line-height: var(--ui-leading-relaxed);
  font-size: var(--ui-text-body);
  color: var(--ui-text);
}

.intro-content p {
  margin-bottom: var(--ui-gap-md);
}

.intro-content p:last-child {
  margin-bottom: 0;
}

.intro-content strong {
  font-weight: var(--ui-weight-semibold);
  color: var(--ui-text);
}

.intro-content ul {
  margin-left: var(--ui-gap-xl);
  margin-bottom: var(--ui-gap-md);
  list-style-type: disc;
}

.intro-content li {
  margin-bottom: var(--ui-gap-sm);
  color: var(--ui-text-secondary);
}

/**
 * Category-specific SEO introduction content
 * Used on: Category pages
 */
.category-intro {
  margin: var(--ui-gap-xl) 0;
  padding: var(--ui-padding-lg);
  background: var(--ui-bg);
  border-radius: var(--ui-radius-md);
  border: 1px solid var(--ui-border);
  line-height: var(--ui-leading-relaxed);
  font-size: var(--ui-text-body);
  color: var(--ui-text);
}

.category-intro p {
  margin-bottom: var(--ui-gap-md);
}

.category-intro p:last-child {
  margin-bottom: 0;
}

.category-intro strong {
  font-weight: var(--ui-weight-semibold);
  color: var(--ui-text);
}

.category-intro ul {
  margin-left: var(--ui-gap-xl);
  margin-bottom: var(--ui-gap-md);
  list-style-type: disc;
}

.category-intro li {
  margin-bottom: var(--ui-gap-sm);
  color: var(--ui-text-secondary);
}

/* Hide intro content when printing */
@media print {
  .intro-content,
  .category-intro {
    display: none;
  }
}

/* Responsive adjustments for mobile */
@media (max-width: 768px) {
  .intro-content,
  .category-intro {
    margin: var(--ui-gap-lg) 0;
    padding: var(--ui-padding-md);
    font-size: var(--ui-text-small);
  }
}

/* ==========================================================================
   SEO CONTENT LAYOUT - INTRO BRIEF & LEARNING GUIDE
   Extracted from inline styles for Frontend Asset Independence compliance
   ========================================================================== */

/**
 * Brief Introduction Box (Top Section)
 * Used on: Home, Category, Content pages
 * Displays first paragraph of SEO content
 * Theme-aware: Uses --ui-* tokens that respond to theme switcher
 */
.intro-brief {
  margin: 1.5rem auto;
  max-width: var(--ui-page-max-width);
  padding: 1rem 1.25rem;
  background: linear-gradient(135deg, var(--ui-bg-subtle) 0%, var(--ui-bg-muted) 100%);
  border-left: 4px solid var(--ui-link);
  border-radius: var(--ui-radius-btn);
  font-size: 1rem;
  line-height: 1.6;
  color: var(--ui-text);
}

.intro-brief p {
  margin: 0.75rem 0;
}

.intro-brief p:first-child {
  margin-top: 0;
}

.intro-brief p:last-child {
  margin-bottom: 0;
}

/**
 * Learning Guide Box (Bottom Section)
 * Used on: Home, Category, Content pages
 * Displays detailed SEO content with teaching tips
 *
 * Theme-aware: Uses --ui-* tokens that respond to theme switcher
 */
.learning-guide {
  margin: 1.5rem auto 1rem;
  max-width: var(--ui-page-max-width);
  padding: 1.25rem;
  /* Theme-aware background using UI tokens */
  background: linear-gradient(135deg, var(--ui-bg-muted) 0%, var(--ui-bg-accent) 100%);
  border: 1px solid var(--ui-border);
  border-radius: var(--ui-radius-md);
  box-shadow: var(--ui-shadow-card);
}

.learning-guide-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1rem;
  padding-bottom: 0.75rem;
  border-bottom: 2px solid var(--ui-border);
}

.learning-guide-header .icon {
  width: 1.5rem;
  height: 1.5rem;
  color: var(--ui-link);
  fill: var(--ui-link);
}

.learning-guide-header h2 {
  margin: 0;
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--ui-text);
}

.learning-guide-content {
  font-size: 0.95rem;
  line-height: 1.7;
  color: var(--ui-text-muted);
}

.learning-guide-content p {
  margin: 0.75rem 0;
}

.learning-guide-content p:first-child {
  margin-top: 0;
}

.learning-guide-content p:last-child {
  margin-bottom: 0;
}

.learning-guide-content strong {
  color: var(--ui-text);
  font-weight: 600;
}

.learning-guide-content ul,
.learning-guide-content ol {
  margin: 0.75rem 0;
  padding-left: 1.5rem;
}

.learning-guide-content li {
  margin: 0.5rem 0;
}

/**
 * SEO Body Section (Bottom of pages)
 * Used on: Home, Category, Content pages
 * Contains detailed SEO article content
 *
 * Theme-aware: Uses --ui-* tokens that respond to theme switcher
 */
.v7-seo-body {
  margin: 2rem auto 1.5rem;
  padding: 1.5rem;
  background: linear-gradient(135deg, var(--ui-bg-muted) 0%, var(--ui-bg-subtle) 100%);
  border: 1px solid var(--ui-border);
  border-radius: var(--ui-radius-md);
  box-shadow: var(--ui-shadow-card);
}

.v7-seo-body-content {
  max-width: 100%;
}

.seo-article {
  font-size: 0.95rem;
  line-height: 1.7;
  color: var(--ui-text-muted);
}

.seo-article h2 {
  margin: 0 0 1rem;
  padding-bottom: 0.75rem;
  border-bottom: 2px solid var(--ui-border);
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--ui-text);
}

.seo-article h3 {
  margin: 1.5rem 0 0.75rem;
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--ui-text);
}

.seo-article p {
  margin: 0.75rem 0;
}

.seo-article p:last-child {
  margin-bottom: 0;
}

.seo-article strong {
  color: var(--ui-text);
  font-weight: 600;
}

.seo-article ul,
.seo-article ol {
  margin: 0.75rem 0;
  padding-left: 1.5rem;
}

.seo-article li {
  margin: 0.5rem 0;
}

/* Dark theme adjustments for SEO body */
[data-theme="dark"] .v7-seo-body {
  background: linear-gradient(135deg, var(--ui-bg-muted) 0%, var(--ui-bg-accent) 100%);
  border-color: var(--ui-border);
}

[data-theme="dark"] .seo-article {
  color: var(--ui-text-muted);
}

[data-theme="dark"] .seo-article h2,
[data-theme="dark"] .seo-article h3,
[data-theme="dark"] .seo-article strong {
  color: var(--ui-text);
}

/* Responsive adjustments for SEO body */
@media (max-width: 768px) {
  .v7-seo-body {
    margin: 1.5rem auto 1rem;
    padding: 1rem;
  }

  .seo-article {
    font-size: 0.9rem;
  }

  .seo-article h2 {
    font-size: 1.125rem;
  }

  .seo-article h3 {
    font-size: 1rem;
  }
}

/* Hide SEO sections when printing (handled in print.css) */
@media print {
  .intro-brief,
  .learning-guide,
  .site-info-box:not(.print-visible),
  .screen-only {
    display: none !important;
  }
}

/* Responsive adjustments for intro-brief and learning-guide */
@media (max-width: 768px) {
  .intro-brief {
    padding: 0.875rem 1rem;
    font-size: 0.9375rem;
    margin: 1.25rem auto;
  }

  .learning-guide {
    padding: 1.25rem;
    margin: 2rem auto 1.5rem;
  }

  .learning-guide-header h2 {
    font-size: 1.125rem;
  }

  .learning-guide-content {
    font-size: 0.875rem;
  }
}

/* Dark theme specific adjustments for better contrast */
[data-theme="dark"] .intro-brief {
  background: linear-gradient(135deg, #252525 0%, #1e1e1e 100%);
  border-left-color: #64b5f6;
  color: #e0e0e0;
}

[data-theme="dark"] .learning-guide {
  background: linear-gradient(135deg, #1e1e1e 0%, #252525 100%);
  border-color: #404040;
}

[data-theme="dark"] .learning-guide-header {
  border-bottom-color: #404040;
}

[data-theme="dark"] .learning-guide-header .icon {
  color: #64b5f6;
  fill: #64b5f6;
}

[data-theme="dark"] .learning-guide-header h2 {
  color: #e0e0e0;
}

[data-theme="dark"] .learning-guide-content {
  color: #b0b0b0;
}

[data-theme="dark"] .learning-guide-content strong {
  color: #e0e0e0;
}


/* ==========================================================================
   SITE INFO BOX - 通用提示框 (变量驱动)

   "一套逻辑，两张面孔":
   - 屏幕模式：背景色、边框色由 CSS 变量控制，支持站点级自定义
   - 打印模式：自动变为无背景、细黑边框的简洁模式

   使用方式:
   - 默认使用站点主色调 (--site-primary)
   - 添加 .site-info-box--accent 使用强调色
   - 添加 .site-info-box--muted 使用柔和色
   - 添加 .print-visible 在打印时保留显示
   ========================================================================== */

.site-info-box {
  --_info-bg: var(--site-info-bg, var(--ui-bg-muted));
  --_info-border: var(--site-info-border, var(--site-primary, var(--ui-link)));
  --_info-text: var(--site-info-text, var(--ui-text));
  --_info-text-muted: var(--site-info-text-muted, var(--ui-text-muted));

  margin: 1.5rem auto;
  max-width: var(--ui-page-max-width);
  padding: 1.25rem 1.5rem;
  background: var(--_info-bg);
  border-left: 4px solid var(--_info-border);
  border-radius: var(--ui-radius-md);
  color: var(--_info-text);
  font-size: 1rem;
  line-height: 1.6;
}

.site-info-box--accent {
  --_info-bg: linear-gradient(135deg, var(--ui-bg-subtle) 0%, var(--ui-bg-accent) 100%);
  --_info-border: var(--site-accent, var(--ui-link));
}

.site-info-box--muted {
  --_info-bg: var(--ui-bg-subtle);
  --_info-border: var(--ui-border);
}

.site-info-box--card {
  border-left: none;
  border: 1px solid var(--_info-border);
  box-shadow: var(--ui-shadow-sm);
}

.site-info-box__header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.75rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--ui-border-muted);
}

.site-info-box__icon {
  width: 1.5rem;
  height: 1.5rem;
  color: var(--_info-border);
  fill: var(--_info-border);
  flex-shrink: 0;
}

.site-info-box__title {
  margin: 0;
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--_info-text);
}

.site-info-box__content {
  color: var(--_info-text-muted);
}

.site-info-box__content p {
  margin: 0.5rem 0;
}

.site-info-box__content p:first-child {
  margin-top: 0;
}

.site-info-box__content p:last-child {
  margin-bottom: 0;
}

.site-info-box__content strong {
  color: var(--_info-text);
  font-weight: 600;
}

.site-info-box__content ul,
.site-info-box__content ol {
  margin: 0.5rem 0;
  padding-left: 1.5rem;
}

.site-info-box__content li {
  margin: 0.25rem 0;
}

/* Dark theme for site-info-box */
[data-theme="dark"] .site-info-box {
  --_info-bg: linear-gradient(135deg, #1e1e1e 0%, #252525 100%);
  --_info-border: #64b5f6;
  --_info-text: #e0e0e0;
  --_info-text-muted: #b0b0b0;
}

/* Responsive */
@media (max-width: 768px) {
  .site-info-box {
    padding: 1rem 1.25rem;
    font-size: 0.9375rem;
    margin: 1.25rem auto;
  }

  .site-info-box__title {
    font-size: 1rem;
  }
}

/* ==========================================================================
   UTILITY CLASSES - 内容自适应 & App 兼容性
   ========================================================================== */

/* Width Utilities - "呼吸感"设计 */
.w-fit { width: var(--ui-width-fit); }      /* 自动收缩到内容宽度 */
.w-auto { width: var(--ui-width-auto); }
.w-full { width: var(--ui-width-full); }

/* Max-Width Containers */
.max-w-xs { max-width: var(--ui-container-xs); }
.max-w-sm { max-width: var(--ui-container-sm); }
.max-w-md { max-width: var(--ui-container-md); }
.max-w-lg { max-width: var(--ui-container-lg); }
.max-w-xl { max-width: var(--ui-container-xl); }
.max-w-full { max-width: var(--ui-container-full); }

/* Responsive Container - App 兼容性 */
.container-responsive {
  width: 100%;
  max-width: var(--ui-container-lg);
  margin-inline: auto;
  padding-inline: var(--ui-page-padding);
}

/* Mobile-First: 所有宽度在手机上变成 100% 垂直排列 */
@media (max-width: 768px) {
  .mobile-full {
    width: var(--ui-width-full) !important;
    max-width: none !important;
  }

  .mobile-stack {
    flex-direction: column !important;
    align-items: stretch !important;
  }

  .mobile-stack > * {
    width: var(--ui-width-full);
  }
}

/* Tight content boxes - 文字少的框自动收缩 */
.compact-box {
  width: var(--ui-width-fit);
  max-width: var(--ui-container-md);
}

/* Wide content boxes - 文字多的框可以宽一点 */
.wide-box {
  width: 100%;
  max-width: var(--ui-container-lg);
}

/* ==========================================================================
   SITE-SPECIFIC THEMING (Mother Architecture)
   Uses CSS variables injected from site config: --site-primary, --site-secondary, --site-accent
   ========================================================================== */

/* Site Header - Light Background with Themed Accents
   Background follows theme (--ui-bg), text/links use site primary color */
.site-header {
  background: var(--ui-bg);
  border-bottom: 2px solid color-mix(in srgb, var(--site-primary) 30%, transparent);
  padding: var(--ui-padding-md) var(--ui-padding-lg);
  box-shadow: var(--ui-shadow-card);
}

.site-header .logo-text {
  color: var(--site-primary);
  font-family: var(--ui-font-heading);
  font-weight: 700;
  font-size: 1.25rem;
}

.site-header .header-nav .nav-link {
  color: var(--ui-text);
  font-weight: 500;
  padding: var(--ui-padding-sm) var(--ui-padding-md);
  border-radius: var(--ui-radius-btn);
  transition: all 0.2s ease;
}

.site-header .header-nav .nav-link:hover {
  background: color-mix(in srgb, var(--site-primary) 10%, transparent);
  color: var(--site-primary);
}

.site-header .header-nav .nav-link.active {
  background: color-mix(in srgb, var(--site-primary) 15%, transparent);
  color: var(--site-primary);
  font-weight: 600;
}

/* Language Switcher in Header */
.site-header .language-btn {
  background: var(--ui-bg-subtle);
  border: 1px solid var(--ui-border);
  color: var(--ui-text);
}

.site-header .language-btn:hover {
  background: color-mix(in srgb, var(--site-primary) 10%, transparent);
  border-color: var(--site-primary);
}

/* Theme Dots in Header */
.site-header .theme-dot {
  border: 2px solid var(--ui-border);
}

.site-header .theme-dot.active {
  border-color: var(--site-primary);
  box-shadow: 0 0 0 2px color-mix(in srgb, var(--site-primary) 30%, transparent);
}

/* ==========================================================================
   MATH SITE SPECIFIC (data-site="math")
   All colors use --site-* variables from site config
   ========================================================================== */

[data-site="math"] .problem-grid {
  gap: 1.5rem 2rem;
  padding: 2rem;
  background: linear-gradient(135deg, var(--ui-bg) 0%, var(--ui-bg-subtle) 100%);
  border: 2px solid var(--site-primary);
  border-radius: var(--ui-radius-md);
}

[data-site="math"] .problem-card {
  background: var(--ui-bg);
  border: 2px solid var(--ui-border);
  border-radius: var(--ui-radius-md);
  padding: 1.5rem;
  box-shadow: var(--ui-shadow-card);
  transition: all 0.2s ease;
}

[data-site="math"] .problem-card:hover {
  border-color: var(--site-primary);
  box-shadow: var(--ui-shadow-card-hover);
  transform: translateY(-2px);
}

/* Math-specific typography - Clear, professional numbers */
[data-site="math"] .problem-content {
  font-family: var(--ui-font-code);
  font-size: 1.75rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  color: var(--ui-text);
}

[data-site="math"] .problem-content .operand {
  min-width: 2.5ch;
  text-align: right;
  display: inline-block;
}

[data-site="math"] .problem-content .operator {
  color: var(--site-primary);
  font-weight: 700;
  margin: 0 0.5rem;
}

[data-site="math"] .problem-content .equals {
  color: var(--site-secondary);
  margin: 0 0.5rem;
}

/* Math Answer Blank - Uses site-primary, NOT site-accent (禁止橙色) */
[data-site="math"] .problem-content .answer-blank {
  display: inline-block;
  min-width: 3ch;
  border-bottom: 2px solid var(--site-primary);
  margin-left: 0.25rem;
}

/* Math Problem Number Badge - Flexbox 居中，禁止负偏移定位 */
[data-site="math"] .problem-number {
  position: absolute;
  top: 8px;
  left: 8px;
  background: color-mix(in srgb, var(--site-primary) 15%, transparent);
  color: var(--site-primary);
  width: 24px;
  height: 24px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  font-weight: 700;
  border: 1.5px solid var(--site-primary);
}

/* Math Action Buttons */
[data-site="math"] .action-btn.primary {
  background: linear-gradient(135deg, var(--site-primary) 0%, color-mix(in srgb, var(--site-primary) 85%, #000) 100%);
  border: none;
  color: var(--ui-text-inverse);
  font-weight: 600;
  padding: 0.75rem 1.5rem;
  border-radius: var(--ui-radius-btn);
  box-shadow: 0 4px 12px color-mix(in srgb, var(--site-primary) 25%, transparent);
}

[data-site="math"] .action-btn.primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 16px color-mix(in srgb, var(--site-primary) 35%, transparent);
}

[data-site="math"] .action-btn.secondary {
  background: var(--site-secondary);
  border: none;
  color: var(--ui-text-inverse);
}

[data-site="math"] .action-btn.outline {
  border: 2px solid var(--site-primary);
  color: var(--site-primary);
  background: transparent;
}

[data-site="math"] .action-btn.outline:hover {
  background: var(--site-primary);
  color: var(--ui-text-inverse);
}

/* Math Topic Cards */
[data-site="math"] .topic-card {
  border: 2px solid transparent;
  background: linear-gradient(var(--ui-bg), var(--ui-bg)) padding-box,
              linear-gradient(135deg, var(--site-primary), var(--site-secondary)) border-box;
  border-radius: var(--ui-radius-md);
  transition: all 0.3s ease;
}

[data-site="math"] .topic-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 24px color-mix(in srgb, var(--site-primary) 20%, transparent);
}

[data-site="math"] .topic-icon {
  color: var(--site-primary);
}

/* Math Answer Key */
[data-site="math"] .answer-key {
  background: linear-gradient(
    135deg,
    color-mix(in srgb, var(--site-secondary) 8%, #fff) 0%,
    color-mix(in srgb, var(--site-secondary) 15%, #fff) 100%
  );
  border: 2px solid var(--site-secondary);
  border-radius: var(--ui-radius-md);
  margin-top: 2rem;
}

[data-site="math"] .answer-key summary {
  color: var(--site-secondary);
  font-weight: 600;
  padding: 1rem 1.5rem;
  cursor: pointer;
}

[data-site="math"] .answer-key .answer-grid {
  padding: 1rem 1.5rem;
}

[data-site="math"] .answer-key .answer-value {
  font-family: var(--ui-font-code);
  font-weight: 600;
  color: var(--site-secondary);
}

/* ==========================================================================
   SUDOKU SITE SPECIFIC (data-site="sudoku")
   Uses --site-* variables injected from site config
   ========================================================================== */

[data-site="sudoku"] .site-header {
  /* Sudoku uses same light header style, colors come from --site-* */
}

[data-site="sudoku"] .problem-grid {
  gap: 0;
  padding: 0;
  background: transparent;
  border: none;
}

[data-site="sudoku"] .problem-card {
  background: var(--ui-bg);
  border: 2px solid var(--ui-border);
  border-radius: var(--ui-radius-sm);
  aspect-ratio: 1;
}

[data-site="sudoku"] .topic-card {
  background: linear-gradient(
    135deg,
    color-mix(in srgb, var(--site-primary) 10%, var(--ui-bg)) 0%,
    color-mix(in srgb, var(--site-secondary) 10%, var(--ui-bg)) 100%
  );
  color: var(--ui-text);
  border: 2px solid var(--site-accent);
}

[data-site="sudoku"] .topic-card:hover {
  border-color: var(--site-accent);
  box-shadow: 0 8px 24px color-mix(in srgb, var(--site-accent) 30%, transparent);
}

[data-site="sudoku"] .topic-name {
  color: var(--ui-text);
}

[data-site="sudoku"] .topic-icon {
  color: var(--site-accent);
}

/* ======== Sudoku Grid Enhancement (Design Spec §2) ======== */
[data-site="sudoku"] .sudoku-grid {
  border: 3px solid #1e293b;
  border-radius: 4px;
  background: #1e293b;
  box-shadow: var(--ui-shadow-md);
}

[data-site="sudoku"] .sudoku-cell {
  transition: background-color 150ms ease, transform 100ms ease;
  font-family: 'Inter', var(--font-sans);
}

[data-site="sudoku"] .sudoku-cell:hover:not(.given) {
  background-color: var(--ui-state-hover-bg, #eff6ff);
  transform: scale(1.02);
  z-index: 1;
}

[data-site="sudoku"] .sudoku-cell.given {
  color: var(--sudoku-cell-text-given, #1e293b);
  font-weight: 700;
}

[data-site="sudoku"] .sudoku-cell.empty {
  color: var(--sudoku-cell-text-user, #2563eb);
}

/* ======== Container Cards with Shadow (Design Spec §4.3) ======== */
/* 注意：排除 header 和 breadcrumb 内的 v7-container，它们不需要卡片样式 */
[data-site="sudoku"] main .v7-container,
[data-site="sudoku"] .content-page,
[data-site="sudoku"] .generated-content,
[data-site="sudoku"] .worksheet-content {
  box-shadow: var(--ui-shadow-card);
  border-radius: var(--ui-radius-lg);
  padding: var(--ui-padding-card);
  margin-bottom: var(--ui-margin-card);
  background: var(--ui-bg);
}

/* 确保 header 和 breadcrumb 内的容器不受卡片样式影响 */
[data-site="sudoku"] .site-header .v7-container,
[data-site="sudoku"] .site-header .header-inner,
[data-site="sudoku"] .breadcrumb-bar .v7-container {
  box-shadow: none;
  border-radius: 0;
  padding: 0;
  margin-bottom: 0;
  background: transparent;
}

/* ======== Problem Card Hover Effect (Design Spec §4.3) ======== */
[data-site="sudoku"] .v7-problem-card {
  transition: box-shadow 200ms ease, transform 200ms ease;
  padding: 1rem;
  border-radius: var(--ui-radius-md);
}

[data-site="sudoku"] .v7-problem-card:hover {
  box-shadow: var(--ui-shadow-hover);
  transform: translateY(-2px);
}

/* ======== Set Switcher Blue Highlight (Design Spec §6.1) ======== */
[data-site="sudoku"] .set-switcher .set-btn {
  background: var(--ui-bg-muted);
  color: var(--ui-text-muted);
  border: 1px solid var(--ui-border-muted);
  transition: all 150ms ease;
}

[data-site="sudoku"] .set-switcher .set-btn:hover {
  background: var(--ui-state-hover-bg);
  border-color: var(--sudoku-primary, #2563eb);
  color: var(--sudoku-primary, #2563eb);
}

[data-site="sudoku"] .set-switcher .set-btn.current,
[data-site="sudoku"] .set-switcher .set-btn[aria-current="true"] {
  background: var(--sudoku-primary, #2563eb);
  color: white;
  border-color: var(--sudoku-primary, #2563eb);
  font-weight: 600;
}

/* ======== Page Title Gradient ======== */
[data-site="sudoku"] .page-title,
[data-site="sudoku"] h1 {
  background: linear-gradient(135deg, var(--sudoku-primary) 0%, var(--sudoku-accent) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* ======== Neon Theme Glow Effects (Sudoku) ======== */
[data-site="sudoku"][data-theme="neon"] .action-btn,
[data-site="sudoku"][data-theme="neon"] button,
[data-site="sudoku"][data-theme="neon"] .set-btn {
  box-shadow: 0 0 10px var(--neon-glow, #a855f7);
  border-color: var(--neon-glow, #a855f7);
  transition: box-shadow 200ms ease, transform 200ms ease;
}

[data-site="sudoku"][data-theme="neon"] .action-btn:hover,
[data-site="sudoku"][data-theme="neon"] button:hover,
[data-site="sudoku"][data-theme="neon"] .set-btn:hover {
  box-shadow: 0 0 20px var(--neon-glow-strong, #ff00e5), 0 0 40px var(--neon-glow, #a855f7);
  transform: translateY(-2px);
}

[data-site="sudoku"][data-theme="neon"] .action-btn.primary {
  background: linear-gradient(135deg, #ff00e5 0%, #a855f7 100%);
  border: none;
  box-shadow: 0 0 15px #ff00e5, 0 0 30px #a855f7;
}

[data-site="sudoku"][data-theme="neon"] input,
[data-site="sudoku"][data-theme="neon"] .sudoku-cell:focus {
  box-shadow: 0 0 10px var(--neon-glow, #a855f7);
  outline: 2px solid var(--neon-glow, #a855f7);
}

/* Neon theme headings with fluorescent color */
[data-site="sudoku"][data-theme="neon"] h1,
[data-site="sudoku"][data-theme="neon"] h2,
[data-site="sudoku"][data-theme="neon"] .page-title {
  background: linear-gradient(135deg, #00f2ff 0%, #ff00e5 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-shadow: 0 0 30px rgba(0, 242, 255, 0.5);
}

/* Neon theme sudoku grid glow */
[data-site="sudoku"][data-theme="neon"] .sudoku-grid {
  box-shadow: 0 0 20px var(--neon-glow, #a855f7), 0 0 40px rgba(168, 85, 247, 0.3);
  border-color: var(--neon-glow-strong, #ff00e5);
}

/* ======== Graphite Theme Adjustments (Sudoku) ======== */
[data-site="sudoku"][data-theme="graphite"] h1,
[data-site="sudoku"][data-theme="graphite"] h2,
[data-site="sudoku"][data-theme="graphite"] .page-title {
  background: none;
  -webkit-text-fill-color: var(--ui-text);
  color: var(--ui-text);
}

[data-site="sudoku"][data-theme="graphite"] .sudoku-grid {
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}

/* ======== Responsive Spacing (Design Spec §7) ======== */
@media (max-width: 768px) {
  [data-site="sudoku"] {
    --ui-padding-card: 16px;
    --ui-padding-section: 20px;
    --ui-margin-card: 16px;
    --ui-gap-grid: 16px;
  }
}

@media (max-width: 480px) {
  [data-site="sudoku"] {
    --ui-padding-card: 12px;
    --ui-padding-section: 16px;
  }
}

/* ==========================================================================
   VALUE SECTION ENHANCEMENT
   ========================================================================== */

.value-section {
  margin: 3rem 0;
  padding: 2rem;
  background: linear-gradient(135deg, var(--ui-bg-muted) 0%, var(--ui-bg-subtle) 100%);
  border-radius: var(--ui-radius-md);
  border: 1px solid var(--ui-border-muted);
}

.value-grid {
  display: flex;
  justify-content: center;
  gap: 4rem;
  flex-wrap: wrap;
}

.value-item {
  text-align: center;
}

.value-number {
  display: block;
  font-size: 2.5rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--site-primary) 0%, var(--site-secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.value-label {
  display: block;
  font-size: 0.875rem;
  color: var(--ui-text-muted);
  font-weight: 500;
  margin-top: 0.25rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* ==========================================================================
   HERO SECTION ENHANCEMENT
   ========================================================================== */

.hero-title {
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 800;
  background: linear-gradient(135deg, var(--site-primary) 0%, var(--site-secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 1rem;
  line-height: 1.2;
}

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--ui-text-muted);
  max-width: 600px;
  margin: 0 auto 2rem;
}

/* ==========================================================================
   RESPONSIVE ADJUSTMENTS FOR THEMED COMPONENTS
   ========================================================================== */

@media (max-width: 768px) {
  .site-header {
    flex-wrap: wrap;
    padding: var(--ui-padding-sm) var(--ui-padding-md);
  }

  .site-header .header-nav {
    order: 3;
    width: 100%;
    justify-content: center;
    margin-top: var(--ui-gap-sm);
    overflow-x: auto;
    padding: var(--ui-padding-xs) 0;
  }

  .site-header .header-nav .nav-link {
    padding: var(--ui-padding-xs) var(--ui-padding-sm);
    font-size: 0.875rem;
  }

  [data-site="math"] .problem-content {
    font-size: 1.5rem;
  }

  [data-site="math"] .problem-grid {
    gap: 1rem;
    padding: 1rem;
  }

  .value-grid {
    gap: 2rem;
  }

  .value-number {
    font-size: 2rem;
  }
}

@media (max-width: 480px) {
  [data-site="math"] .problem-content {
    font-size: 1.25rem;
  }

  .hero-title {
    font-size: 1.75rem;
  }

  .hero-subtitle {
    font-size: 1rem;
  }
}

/* ==========================================================================
   THEME-AWARE INTRO BRIEF & PAGE COMPONENTS (Mother Architecture)
   Uses --site-primary, --site-secondary, --site-accent from site config
   ========================================================================== */

/* Math Site - Page Title with Theme Gradient */
[data-site="math"] .page-title {
  background: linear-gradient(135deg, var(--site-primary) 0%, var(--site-secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* Math Site - Category Header Enhancement */
[data-site="math"] .category-header {
  margin-bottom: 2rem;
}

[data-site="math"] .category-header .page-icon {
  font-size: 2.5rem;
  margin-bottom: 0.75rem;
  display: block;
}

/* Math Site - Subcategory Cards with Theme Colors */
[data-site="math"] .subcategory-card {
  border: 2px solid var(--ui-border-muted);
  background: var(--ui-bg);
  border-radius: 12px;
  padding: 1.25rem 1.5rem;
  transition: all 0.2s ease;
}

[data-site="math"] .subcategory-card:hover {
  border-color: var(--site-primary);
  box-shadow: 0 4px 16px rgba(79, 70, 229, 0.15);
  transform: translateY(-2px);
}

[data-site="math"] .subcategory-card:hover .subcategory-name {
  color: var(--site-primary);
}

[data-site="math"] .subcategory-count {
  background: color-mix(in srgb, var(--site-primary) 15%, #fff);
  color: var(--site-primary);
  font-weight: 600;
}

/* Math Site - Sibling Tabs with Theme Colors */
[data-site="math"] .sibling-tab {
  border: 2px solid var(--ui-border-muted);
  background: var(--ui-bg);
  color: var(--ui-text);
  padding: 0.625rem 1.25rem;
  border-radius: 8px;
  font-weight: 500;
  transition: all 0.2s ease;
}

[data-site="math"] .sibling-tab:hover {
  border-color: var(--site-primary);
  color: var(--site-primary);
}

[data-site="math"] .sibling-tab.active {
  background: linear-gradient(135deg, var(--site-primary) 0%, color-mix(in srgb, var(--site-primary) 85%, #000) 100%);
  border-color: var(--site-primary);
  color: #ffffff;
  font-weight: 600;
  box-shadow: 0 2px 8px rgba(79, 70, 229, 0.25);
}

/* Math Site - Breadcrumb Enhancement */
[data-site="math"] .breadcrumb-link:hover {
  color: var(--site-primary);
}

[data-site="math"] .breadcrumb-current {
  color: var(--site-primary);
  font-weight: 600;
}

[data-site="sudoku"] .page-title {
  background: linear-gradient(135deg, var(--site-primary) 0%, var(--site-accent) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* ==========================================================================
   SUDOKU UNIQUE CARD STYLES - 10 Distinct Designs
   Based on difficulty levels and grid sizes
   ========================================================================== */

/* Base card style for sudoku */
[data-site="sudoku"] .subcategory-card {
  position: relative;
  overflow: hidden;
  border: 2px solid transparent;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-site="sudoku"] .subcategory-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  transition: height 0.3s ease;
}

[data-site="sudoku"] .subcategory-card:hover::before {
  height: 100%;
  opacity: 0.1;
}

/* ======== DIFFICULTY STYLES ======== */

/* 1. Easy - Fresh Green with leaf pattern */
[data-site="sudoku"] .subcategory-card[href*="/easy"] {
  background: linear-gradient(135deg, #ecfdf5 0%, #d1fae5 100%);
  border-color: #10b981;
}
[data-site="sudoku"] .subcategory-card[href*="/easy"]::before {
  background: linear-gradient(90deg, #10b981, #34d399);
}
[data-site="sudoku"] .subcategory-card[href*="/easy"] .subcategory-name {
  color: #047857;
}
[data-site="sudoku"] .subcategory-card[href*="/easy"] .subcategory-icon {
  color: #10b981;
}
[data-site="sudoku"] .subcategory-card[href*="/easy"]:hover {
  border-color: #059669;
  box-shadow: 0 8px 24px rgba(16, 185, 129, 0.25);
  transform: translateY(-4px);
}

/* 2. Medium - Warm Amber with sun glow */
[data-site="sudoku"] .subcategory-card[href*="/medium"] {
  background: linear-gradient(135deg, #fffbeb 0%, #fef3c7 100%);
  border-color: #f59e0b;
}
[data-site="sudoku"] .subcategory-card[href*="/medium"]::before {
  background: linear-gradient(90deg, #f59e0b, #fbbf24);
}
[data-site="sudoku"] .subcategory-card[href*="/medium"] .subcategory-name {
  color: #b45309;
}
[data-site="sudoku"] .subcategory-card[href*="/medium"] .subcategory-icon {
  color: #f59e0b;
}
[data-site="sudoku"] .subcategory-card[href*="/medium"]:hover {
  border-color: #d97706;
  box-shadow: 0 8px 24px rgba(245, 158, 11, 0.25);
  transform: translateY(-4px);
}

/* 3. Hard - Hot Orange with fire effect */
[data-site="sudoku"] .subcategory-card[href*="/hard"] {
  background: linear-gradient(135deg, #fff7ed 0%, #ffedd5 100%);
  border-color: #f97316;
}
[data-site="sudoku"] .subcategory-card[href*="/hard"]::before {
  background: linear-gradient(90deg, #f97316, #fb923c);
}
[data-site="sudoku"] .subcategory-card[href*="/hard"] .subcategory-name {
  color: #c2410c;
}
[data-site="sudoku"] .subcategory-card[href*="/hard"] .subcategory-icon {
  color: #f97316;
}
[data-site="sudoku"] .subcategory-card[href*="/hard"]:hover {
  border-color: #ea580c;
  box-shadow: 0 8px 24px rgba(249, 115, 22, 0.25);
  transform: translateY(-4px);
}

/* 4. Expert - Intense Red with pulse */
[data-site="sudoku"] .subcategory-card[href*="/expert"] {
  background: linear-gradient(135deg, #fef2f2 0%, #fee2e2 100%);
  border-color: #ef4444;
}
[data-site="sudoku"] .subcategory-card[href*="/expert"]::before {
  background: linear-gradient(90deg, #ef4444, #f87171);
}
[data-site="sudoku"] .subcategory-card[href*="/expert"] .subcategory-name {
  color: #b91c1c;
}
[data-site="sudoku"] .subcategory-card[href*="/expert"] .subcategory-icon {
  color: #ef4444;
}
[data-site="sudoku"] .subcategory-card[href*="/expert"]:hover {
  border-color: #dc2626;
  box-shadow: 0 8px 24px rgba(239, 68, 68, 0.25);
  transform: translateY(-4px);
}

/* 5. Crazy - Electric Purple with glow */
[data-site="sudoku"] .subcategory-card[href*="/crazy"] {
  background: linear-gradient(135deg, #faf5ff 0%, #f3e8ff 100%);
  border-color: #a855f7;
}
[data-site="sudoku"] .subcategory-card[href*="/crazy"]::before {
  background: linear-gradient(90deg, #a855f7, #c084fc);
}
[data-site="sudoku"] .subcategory-card[href*="/crazy"] .subcategory-name {
  color: #7e22ce;
}
[data-site="sudoku"] .subcategory-card[href*="/crazy"] .subcategory-icon {
  color: #a855f7;
}
[data-site="sudoku"] .subcategory-card[href*="/crazy"]:hover {
  border-color: #9333ea;
  box-shadow: 0 8px 24px rgba(168, 85, 247, 0.3), 0 0 40px rgba(168, 85, 247, 0.15);
  transform: translateY(-4px);
}

/* ======== GRID SIZE STYLES (Home page cards) ======== */

/* 6. 4x4 - Playful Kids style with rounded corners */
[data-site="sudoku"] .subcategory-card[href*="/4x4"] {
  background: linear-gradient(135deg, #fdf4ff 0%, #fae8ff 100%);
  border-color: #e879f9;
  border-radius: 16px;
}
[data-site="sudoku"] .subcategory-card[href*="/4x4"]::before {
  background: linear-gradient(90deg, #e879f9, #f0abfc);
}
[data-site="sudoku"] .subcategory-card[href*="/4x4"] .subcategory-name {
  color: #a21caf;
}
[data-site="sudoku"] .subcategory-card[href*="/4x4"]:hover {
  border-color: #d946ef;
  box-shadow: 0 8px 24px rgba(232, 121, 249, 0.25);
  transform: translateY(-4px) rotate(1deg);
}

/* 7. 6x6 - Junior style with soft blue */
[data-site="sudoku"] .subcategory-card[href*="/6x6"] {
  background: linear-gradient(135deg, #eff6ff 0%, #dbeafe 100%);
  border-color: #60a5fa;
  border-radius: 12px;
}
[data-site="sudoku"] .subcategory-card[href*="/6x6"]::before {
  background: linear-gradient(90deg, #60a5fa, #93c5fd);
}
[data-site="sudoku"] .subcategory-card[href*="/6x6"] .subcategory-name {
  color: #1d4ed8;
}
[data-site="sudoku"] .subcategory-card[href*="/6x6"]:hover {
  border-color: #3b82f6;
  box-shadow: 0 8px 24px rgba(96, 165, 250, 0.25);
  transform: translateY(-4px);
}

/* 8. 9x9 - Classic style with elegant indigo */
[data-site="sudoku"] .subcategory-card[href*="/9x9"] {
  background: linear-gradient(135deg, #eef2ff 0%, #e0e7ff 100%);
  border-color: #818cf8;
}
[data-site="sudoku"] .subcategory-card[href*="/9x9"]::before {
  background: linear-gradient(90deg, #818cf8, #a5b4fc);
}
[data-site="sudoku"] .subcategory-card[href*="/9x9"] .subcategory-name {
  color: #4338ca;
}
[data-site="sudoku"] .subcategory-card[href*="/9x9"]:hover {
  border-color: #6366f1;
  box-shadow: 0 8px 24px rgba(129, 140, 248, 0.25);
  transform: translateY(-4px);
}

/* 9. 16x16 - Advanced style with teal gradient */
[data-site="sudoku"] .subcategory-card[href*="/16x16"] {
  background: linear-gradient(135deg, #f0fdfa 0%, #ccfbf1 100%);
  border-color: #2dd4bf;
}
[data-site="sudoku"] .subcategory-card[href*="/16x16"]::before {
  background: linear-gradient(90deg, #2dd4bf, #5eead4);
}
[data-site="sudoku"] .subcategory-card[href*="/16x16"] .subcategory-name {
  color: #0f766e;
}
[data-site="sudoku"] .subcategory-card[href*="/16x16"]:hover {
  border-color: #14b8a6;
  box-shadow: 0 8px 24px rgba(45, 212, 191, 0.25);
  transform: translateY(-4px);
}

/* 10. 25x25 & 36x36 - Master/Insane style with dark gradient */
[data-site="sudoku"] .subcategory-card[href*="/25x25"],
[data-site="sudoku"] .subcategory-card[href*="/36x36"] {
  background: linear-gradient(135deg, #1e1b4b 0%, #312e81 100%);
  border-color: #6366f1;
  color: white;
}
[data-site="sudoku"] .subcategory-card[href*="/25x25"]::before,
[data-site="sudoku"] .subcategory-card[href*="/36x36"]::before {
  background: linear-gradient(90deg, #8b5cf6, #a78bfa);
}
[data-site="sudoku"] .subcategory-card[href*="/25x25"] .subcategory-name,
[data-site="sudoku"] .subcategory-card[href*="/36x36"] .subcategory-name {
  color: #e0e7ff;
}
[data-site="sudoku"] .subcategory-card[href*="/25x25"] .subcategory-icon,
[data-site="sudoku"] .subcategory-card[href*="/36x36"] .subcategory-icon {
  color: #a78bfa;
}
[data-site="sudoku"] .subcategory-card[href*="/25x25"] .subcategory-action,
[data-site="sudoku"] .subcategory-card[href*="/36x36"] .subcategory-action {
  color: #c4b5fd;
}
[data-site="sudoku"] .subcategory-card[href*="/25x25"]:hover,
[data-site="sudoku"] .subcategory-card[href*="/36x36"]:hover {
  border-color: #8b5cf6;
  box-shadow: 0 8px 32px rgba(139, 92, 246, 0.4), 0 0 60px rgba(139, 92, 246, 0.2);
  transform: translateY(-4px);
}

/* 36x36 special fire animation */
[data-site="sudoku"] .subcategory-card[href*="/36x36"] {
  background: linear-gradient(135deg, #450a0a 0%, #7f1d1d 50%, #991b1b 100%);
  border-color: #f97316;
  animation: fireGlow 2s ease-in-out infinite alternate;
}
[data-site="sudoku"] .subcategory-card[href*="/36x36"]::before {
  background: linear-gradient(90deg, #f97316, #fbbf24);
}
[data-site="sudoku"] .subcategory-card[href*="/36x36"] .subcategory-name {
  color: #fef3c7;
}
[data-site="sudoku"] .subcategory-card[href*="/36x36"] .subcategory-icon {
  color: #fbbf24;
}
[data-site="sudoku"] .subcategory-card[href*="/36x36"]:hover {
  border-color: #fbbf24;
  box-shadow: 0 8px 32px rgba(249, 115, 22, 0.5), 0 0 60px rgba(251, 191, 36, 0.3);
}

@keyframes fireGlow {
  0% { box-shadow: 0 0 10px rgba(249, 115, 22, 0.3); }
  100% { box-shadow: 0 0 20px rgba(249, 115, 22, 0.5), 0 0 40px rgba(251, 191, 36, 0.2); }
}

[data-site="sudoku"] .subcategory-count {
  background: color-mix(in srgb, var(--site-accent) 15%, #fff);
  color: #6d28d9;
}