/* CSS Variables - Theme System */
:root {
  /* Color palette */
  --color-bg: #ffffff;
  --color-fg: #1a1a2e;
  --color-muted: #6c757d;
  --color-primary: #0066cc;
  --color-primary-hover: #0052a3;
  --color-primary-light: rgba(0, 102, 204, 0.1);
  --color-accent: #00a3a3;
  --color-success: #28a745;
  --color-warning: #ffc107;
  --color-danger: #dc3545;
  --color-border: #dee2e6;
  --color-border-light: #e9ecef;
  --color-card-bg: #ffffff;
  --color-code-bg: #f1f3f5;

  /* Typography */
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans SC", "Noto Sans JP", Roboto, sans-serif;
  --font-mono: "SF Mono", Monaco, Consolas, "Liberation Mono", monospace;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 2rem;

  /* Spacing scale */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.1);
  --shadow-lg: 0 10px 15px rgba(0,0,0,0.1);
  --shadow-xl: 0 20px 25px rgba(0,0,0,0.15);

  /* Radius */
  --radius-sm: 4px;
  --radius: 8px;
  --radius-lg: 12px;
  --radius-full: 9999px;

  /* Layout */
  --container-width: 1200px;
  --header-height: 64px;

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-base: 0.2s ease;
  --transition-slow: 0.3s ease;

  /* Z-index scale */
  --z-header: 100;
  --z-dropdown: 200;
  --z-modal: 1000;
  --z-toast: 1100;
}

[data-theme="dark"] {
  --color-bg: #0a0a1a;
  --color-fg: #e4e4ef;
  --color-muted: #8b8b9a;
  --color-primary: #4d9fff;
  --color-primary-hover: #66b0ff;
  --color-primary-light: rgba(77, 159, 255, 0.15);
  --color-accent: #00d4d4;
  --color-border: #2a2a3e;
  --color-border-light: #1f1f30;
  --color-card-bg: #1a1a2e;
  --color-code-bg: #16162a;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.4);
  --shadow-lg: 0 10px 15px rgba(0,0,0,0.5);
  --shadow-xl: 0 20px 25px rgba(0,0,0,0.6);
}

/* Reset */
*, *::before, *::after { box-sizing: border-box; }
* { margin: 0; padding: 0; }
body {
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-fg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--color-primary); text-decoration: none; }
a:hover { color: var(--color-primary-hover); text-decoration: underline; }
img { max-width: 100%; height: auto; }

/* Container */
.container { max-width: var(--container-width); margin: 0 auto; padding: 0 1rem; }

/* Header */
.site-header {
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  padding: 0.75rem 0;
  position: sticky; top: 0; z-index: 100;
  box-shadow: var(--shadow-sm);
}
.site-header .container {
  display: flex; align-items: center; justify-content: space-between; gap: 1rem;
}
.logo { display: flex; align-items: center; gap: 0.5rem; font-weight: bold; font-size: 1.25rem; color: var(--color-fg); }
.main-nav { display: flex; gap: 1.5rem; }
.main-nav a { color: var(--color-fg); font-weight: 500; }
.header-actions { display: flex; align-items: center; gap: 1rem; }

/* Search Box */
.search-box {
  display: flex; gap: 0.5rem; align-items: center;
}
.search-box input {
  padding: 0.5rem 0.75rem; border: 1px solid var(--color-border);
  border-radius: var(--radius); background: var(--color-bg); color: var(--color-fg);
  font-size: 0.95rem; min-width: 200px;
}
.search-box button { background: none; border: none; cursor: pointer; font-size: 1rem; }

/* Language Switcher */
.language-switcher { position: relative; }
.lang-trigger {
  background: none; border: 1px solid var(--color-border); padding: 0.5rem 0.75rem;
  border-radius: var(--radius); cursor: pointer; color: var(--color-fg);
  display: flex; align-items: center; gap: 0.25rem;
}
.lang-menu {
  display: none; position: absolute; top: 100%; right: 0; min-width: 150px;
  background: var(--color-card-bg); border: 1px solid var(--color-border);
  border-radius: var(--radius); box-shadow: var(--shadow-md); list-style: none;
  padding: 0.25rem 0; z-index: 200;
}
.lang-menu.open { display: block; }
.lang-menu a { display: block; padding: 0.5rem 1rem; color: var(--color-fg); }
.lang-menu a:hover, .lang-menu a.active { background: var(--color-code-bg); }

/* Main */
main.container { padding: 2rem 1rem; min-height: calc(100vh - 200px); }

/* Hero */
.hero { text-align: center; padding: 3rem 0; }
.hero h1 { font-size: 2.5rem; margin-bottom: 1rem; }
.lead { font-size: 1.25rem; color: var(--color-muted); margin-bottom: 2rem; }
.hero .search-box input { min-width: 400px; padding: 0.75rem 1rem; font-size: 1rem; }

/* Stats */
.stats { display: flex; justify-content: center; gap: 2rem; margin: 2rem 0; }
.stat-card { text-align: center; padding: 1rem 2rem; background: var(--color-card-bg); border-radius: var(--radius); box-shadow: var(--shadow-sm); }
.stat-value { display: block; font-size: 2rem; font-weight: bold; color: var(--color-primary); }
.stat-label { color: var(--color-muted); font-size: 0.875rem; }

/* Category Grid */
.category-grid, .term-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1rem; margin: 1.5rem 0;
}
.category-card, .term-card {
  display: block; padding: 1.5rem; background: var(--color-card-bg);
  border: 1px solid var(--color-border); border-radius: var(--radius);
  text-decoration: none; color: var(--color-fg); transition: transform 0.2s, box-shadow 0.2s;
}
.category-card:hover, .term-card:hover {
  transform: translateY(-2px); box-shadow: var(--shadow-md); text-decoration: none;
}
.category-card h3, .term-card h3 { margin-bottom: 0.5rem; color: var(--color-primary); }
.term-definition { color: var(--color-muted); font-size: 0.95rem; margin-bottom: 0.5rem; }
.term-meta { display: flex; gap: 0.5rem; align-items: center; font-size: 0.85rem; }
.badge { background: var(--color-code-bg); padding: 0.25rem 0.5rem; border-radius: 4px; font-size: 0.75rem; }
.badge-preview { background: #fff3cd; color: #856404; }

/* Term Detail */
.term-detail { max-width: 800px; margin: 0 auto; }
.breadcrumb { color: var(--color-muted); margin-bottom: 1rem; font-size: 0.9rem; }
.term-header { border-bottom: 2px solid var(--color-border); padding-bottom: 1rem; margin-bottom: 2rem; }
.term-header h1 { font-size: 2rem; margin-bottom: 0.5rem; }
.term-id { background: var(--color-code-bg); padding: 0.25rem 0.5rem; border-radius: 4px; font-family: var(--font-mono); font-size: 0.9rem; }
.term-content { line-height: 1.8; }
.term-content h2 { margin-top: 2rem; margin-bottom: 1rem; border-bottom: 1px solid var(--color-border); padding-bottom: 0.5rem; }
.term-content ul { margin-left: 1.5rem; margin-bottom: 1rem; }
.term-content code { background: var(--color-code-bg); padding: 0.125rem 0.25rem; border-radius: 3px; font-family: var(--font-mono); }
.term-content pre { background: var(--color-code-bg); padding: 1rem; border-radius: var(--radius); overflow-x: auto; margin: 1rem 0; }

/* Footer */
.site-footer { background: var(--color-card-bg); border-top: 1px solid var(--color-border); padding: 2rem 0; margin-top: 3rem; }
.footer-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 2rem; margin-bottom: 2rem; }
.footer-col h4 { margin-bottom: 0.5rem; }
.footer-col ul { list-style: none; }
.footer-col li { margin-bottom: 0.25rem; }
.footer-bottom { text-align: center; color: var(--color-muted); border-top: 1px solid var(--color-border); padding-top: 1rem; }

/* Responsive */
@media (max-width: 1024px) {
  .container { padding: 0 1.5rem; }
  .hero h1 { font-size: 2.25rem; }
  .footer-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
  :root {
    --font-size-3xl: 1.75rem;
    --font-size-2xl: 1.375rem;
  }
  .site-header .container { flex-wrap: wrap; gap: 0.5rem; }
  .site-header { padding: 0.5rem 0; }
  .logo { font-size: 1.1rem; }
  .logo img { width: 28px; height: 28px; }
  .main-nav { order: 3; width: 100%; justify-content: center; margin-top: 0.5rem; flex-wrap: wrap; gap: 1rem; font-size: 0.9rem; }
  .header-actions { gap: 0.5rem; }
  .search-box input { min-width: 150px; font-size: 0.9rem; }
  main.container { padding: 1.5rem 1rem; }
  .hero { padding: 2rem 0; }
  .hero h1 { font-size: 1.75rem; }
  .lead { font-size: 1.05rem; }
  .hero .search-box input { min-width: 100%; }
  .stats { flex-direction: column; align-items: center; gap: 1rem; }
  .stat-card { padding: 0.75rem 1.5rem; }
  .stat-value { font-size: 1.5rem; }
  .category-grid, .term-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; gap: 1.5rem; }
  .term-detail { max-width: 100%; }
  .term-header h1 { font-size: 1.5rem; }
  .search-page { max-width: 100%; }
}

@media (max-width: 480px) {
  .container { padding: 0 1rem; }
  .main-nav { gap: 0.75rem; font-size: 0.85rem; }
  .hero h1 { font-size: 1.5rem; }
  .hero .search-box input { padding: 0.6rem 0.8rem; }
  .term-content { font-size: 0.95rem; }
  .term-content pre { padding: 0.75rem; font-size: 0.85rem; }
  .search-result-item { padding: 0.75rem; }
  .search-result-title { font-size: 1rem; }
}

/* Touch device optimizations */
@media (hover: none) {
  .category-card:hover, .term-card:hover {
    transform: none;
  }
  .category-card:active, .term-card:active {
    transform: scale(0.98);
  }
}

/* Reduced motion preference */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* RTL Support */
[dir="rtl"] { direction: rtl; }
[dir="rtl"] .main-nav { flex-direction: row-reverse; }

/* Theme Toggle */
.theme-toggle { background: none; border: 1px solid var(--color-border); padding: 0.5rem; border-radius: var(--radius); cursor: pointer; }
[data-theme="dark"] .icon-sun { display: inline; }
[data-theme="dark"] .icon-moon { display: none; }
[data-theme="light"] .icon-sun, :root .icon-sun { display: none; }
[data-theme="light"] .icon-moon, :root .icon-moon { display: inline; }

/* Search Page */
.search-page { max-width: 800px; margin: 0 auto; }
.search-page h1 { margin-bottom: 1rem; }
.search-intro { color: var(--color-muted); margin-bottom: 1.5rem; }
.search-container { position: relative; }
.search-container input[type="search"] {
  width: 100%; padding: 0.75rem 1rem; font-size: 1.05rem;
  border: 1px solid var(--color-border); border-radius: var(--radius);
  background: var(--color-bg); color: var(--color-fg);
}
.search-container input[type="search"]:focus {
  outline: 2px solid var(--color-primary); outline-offset: -1px;
  border-color: var(--color-primary);
}
.search-results { margin-top: 1.5rem; }
.search-count { color: var(--color-muted); margin-bottom: 1rem; font-size: 0.9rem; }
.search-loading, .search-empty, .search-error {
  padding: 1rem; color: var(--color-muted); text-align: center;
}
.search-error { color: #dc3545; }
.search-result-item {
  padding: 1rem 1.25rem; margin-bottom: 0.75rem;
  background: var(--color-card-bg); border: 1px solid var(--color-border);
  border-radius: var(--radius); transition: box-shadow 0.2s;
}
.search-result-item:hover { box-shadow: var(--shadow-sm); }
.search-result-title { margin-bottom: 0.35rem; font-size: 1.1rem; }
.search-result-title a { color: var(--color-primary); }
.search-result-meta {
  display: flex; gap: 0.5rem; flex-wrap: wrap; margin-bottom: 0.5rem;
  font-size: 0.8rem; color: var(--color-muted);
}
.search-term-id, .search-category, .search-lang {
  background: var(--color-code-bg); padding: 0.15rem 0.5rem;
  border-radius: 4px; font-family: var(--font-mono);
}
.search-excerpt {
  color: var(--color-fg); font-size: 0.95rem; line-height: 1.5;
}
.search-excerpt mark {
  background: rgba(255, 235, 59, 0.4); color: inherit;
  padding: 0.05rem 0.15rem; border-radius: 2px;
}

/* Code Highlighting (minimal) */
.term-content pre code { background: transparent; padding: 0; }
.term-content pre code .k { color: #d73a49; }
.term-content pre code .s { color: #032f62; }
.term-content pre code .c { color: #6a737d; font-style: italic; }
[data-theme="dark"] .term-content pre code .k { color: #ff7b72; }
[data-theme="dark"] .term-content pre code .s { color: #a5d6ff; }
[data-theme="dark"] .term-content pre code .c { color: #8b949e; }

/* Card Hover Effects */
.category-card, .term-card {
  position: relative; overflow: hidden;
}
.category-card::after, .term-card::after {
  content: ''; position: absolute; top: 0; left: 0; right: 0; height: 3px;
  background: var(--color-primary); transform: scaleX(0); transform-origin: left;
  transition: transform 0.3s ease;
}
.category-card:hover::after, .term-card:hover::after { transform: scaleX(1); }

/* Focus States for Accessibility */
a:focus-visible, button:focus-visible, input:focus-visible {
  outline: 2px solid var(--color-primary); outline-offset: 2px;
}

/* Print Styles */
@media print {
  .site-header, .site-footer, .search-box, .language-switcher, .theme-toggle { display: none; }
  body { color: #000; background: #fff; }
  a { color: #000; text-decoration: underline; }
}

/* Skip to Content (Accessibility) */
.skip-link {
  position: absolute; top: -40px; left: 0; background: var(--color-primary);
  color: #fff; padding: 0.5rem 1rem; z-index: 999; border-radius: 0 0 var(--radius) 0;
}
.skip-link:focus { top: 0; }