/* =============================================
   C++ Internals — Complete Stylesheet
   Premium dark-first design with light mode
   ============================================= */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=JetBrains+Mono:wght@400;500;700&family=Space+Grotesk:wght@500;600;700&display=swap');

/* =============================================
   CSS Variables / Design Tokens
   ============================================= */
:root {
  /* Dark Theme (Default) */
  --bg-primary: #0d1117;
  --bg-secondary: #161b22;
  --bg-tertiary: #21262d;
  --bg-glass: rgba(13, 17, 23, 0.85);
  --text-primary: #e6edf3;
  --text-secondary: #8b949e;
  --text-muted: #484f58;
  --border-color: #30363d;
  --accent-blue: #58a6ff;
  --accent-purple: #bc8cff;
  --accent-blue-hover: #79c0ff;
  --accent-gradient: linear-gradient(135deg, #58a6ff, #bc8cff);
  --success: #3fb950;
  --warning: #d29922;
  --danger: #f85149;

  --sidebar-width: 280px;
  --header-height: 64px;
  --toc-width: 220px;

  /* Fonts */
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;
  --font-heading: var(--font-body);
  --font-code: 'JetBrains Mono', 'Fira Code', SFMono-Regular, Consolas, monospace;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;

  /* Radii */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.4);
  --shadow-lg: 0 12px 40px rgba(0,0,0,0.5);
  --shadow-glow-blue: 0 0 20px rgba(88, 166, 255, 0.15);
  --shadow-glow-purple: 0 0 20px rgba(188, 140, 255, 0.15);

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-normal: 0.3s ease;
  --transition-slow: 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme='light'] {
  --bg-primary: #ffffff;
  --bg-secondary: #f6f8fa;
  --bg-tertiary: #eaeef2;
  --bg-glass: rgba(255, 255, 255, 0.88);
  --text-primary: #1f2328;
  --text-secondary: #57606a;
  --text-muted: #8c959f;
  --border-color: #d0d7de;
  --accent-blue: #0969da;
  --accent-purple: #8250df;
  --accent-blue-hover: #0550ae;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.08);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.1);
  --shadow-lg: 0 12px 40px rgba(0,0,0,0.12);
  --shadow-glow-blue: 0 0 20px rgba(9, 105, 218, 0.1);
}

/* =============================================
   Reset & Base
   ============================================= */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-body);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  transition: background-color var(--transition-normal), color var(--transition-normal);
  overflow-x: hidden;
  min-height: 100vh;
}

/* Custom Selection */
::selection {
  background-color: rgba(88, 166, 255, 0.3);
  color: var(--text-primary);
}

/* Custom Scrollbar */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}
::-webkit-scrollbar-track {
  background: transparent;
}
::-webkit-scrollbar-thumb {
  background: var(--bg-tertiary);
  border-radius: var(--radius-full);
  border: 2px solid transparent;
}
::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.3;
  color: var(--text-primary);
}

a {
  color: var(--accent-blue);
  text-decoration: none;
  transition: color var(--transition-fast);
}
a:hover {
  color: var(--accent-blue-hover);
}

/* =============================================
   Progress Bar
   ============================================= */
.progress-bar {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  background: var(--accent-gradient);
  z-index: 200;
  width: 0%;
  transition: width 0.1s linear;
}

/* =============================================
   Sidebar
   ============================================= */
.sidebar {
  width: var(--sidebar-width);
  background: var(--bg-secondary);
  border-right: 1px solid var(--border-color);
  position: fixed;
  top: 0;
  bottom: 0;
  left: 0;
  overflow: hidden;
  z-index: 90;
  display: flex;
  flex-direction: column;
  transition: transform var(--transition-normal), box-shadow var(--transition-normal);
}

.sidebar-header {
  padding: var(--space-lg);
  border-bottom: 1px solid var(--border-color);
  flex-shrink: 0;
}

.sidebar-header .logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-family: var(--font-heading);
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
  cursor: pointer;
}

.sidebar-header .logo svg {
  color: var(--accent-blue);
  flex-shrink: 0;
}

.sidebar-header .logo span {
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.sidebar-nav {
  flex: 1 1 auto;
  overflow-y: auto;
  padding: var(--space-md);
  min-height: 0;
  height: 0;
}

.sidebar-home-link {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-weight: 500;
  font-size: 0.9rem;
  margin-bottom: var(--space-md);
  transition: all var(--transition-fast);
}
.sidebar-home-link:hover,
.sidebar-home-link.active {
  color: var(--accent-blue);
  background-color: rgba(88, 166, 255, 0.08);
}
.sidebar-home-link svg {
  flex-shrink: 0;
}

/* Sidebar Categories */
.sidebar-category {
  margin-bottom: var(--space-xs);
}

.sidebar-category-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-sm) var(--space-md);
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  cursor: pointer;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  user-select: none;
}
.sidebar-category-header:hover {
  color: var(--text-secondary);
  background: rgba(255,255,255,0.03);
}

.sidebar-category-header .chevron {
  transition: transform var(--transition-fast);
  flex-shrink: 0;
  opacity: 0.5;
}

.sidebar-category.collapsed .sidebar-category-header .chevron {
  transform: rotate(-90deg);
}

.sidebar-category-topics {
  overflow: hidden;
  max-height: 500px;
  transition: max-height var(--transition-normal);
}

.sidebar-category.collapsed .sidebar-category-topics {
  max-height: 0;
}

.sidebar-link {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: 6px var(--space-md) 6px calc(var(--space-md) + 8px);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-size: 0.875rem;
  transition: all var(--transition-fast);
  position: relative;
  text-decoration: none;
}
.sidebar-link:hover {
  color: var(--text-primary);
  background-color: rgba(255,255,255,0.04);
  transform: translateX(2px);
}
.sidebar-link.active {
  color: var(--accent-blue);
  background-color: rgba(88, 166, 255, 0.1);
  font-weight: 500;
}
.sidebar-link.active::before {
  content: '';
  position: absolute;
  left: 0;
  top: 4px;
  bottom: 4px;
  width: 3px;
  background: var(--accent-gradient);
  border-radius: 0 2px 2px 0;
}

.sidebar-link-dot {
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--text-muted);
  flex-shrink: 0;
  transition: background var(--transition-fast);
}
.sidebar-link:hover .sidebar-link-dot,
.sidebar-link.active .sidebar-link-dot {
  background: var(--accent-blue);
  box-shadow: 0 0 8px rgba(39, 201, 63, 0.5);
}

.sidebar-subtopics-container {
  display: flex;
  flex-direction: column;
  padding-left: 24px;
  margin-top: 4px;
  gap: 4px;
  border-left: 1px solid var(--border-color);
  margin-left: 14px;
  overflow: hidden;
}

.sidebar-subtopics-container.collapsed {
  display: none;
}

.subtopics-chevron {
  margin-left: auto;
  transition: transform var(--transition-fast);
  color: var(--text-muted);
}
.subtopics-chevron:hover {
  color: var(--text-primary);
}
.subtopics-chevron.rotated {
  transform: rotate(-90deg);
}

.sidebar-sublink {
  display: block;
  padding: 6px 12px;
  font-size: 0.85rem;
  color: var(--text-muted);
  text-decoration: none;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

.sidebar-sublink:hover {
  background: var(--bg-hover);
  color: var(--text-primary);
}

.sidebar-sublink.active {
  color: var(--accent-blue);
  font-weight: 500;
}

.sidebar-extra-links {
  margin-top: var(--space-lg);
  padding-top: var(--space-md);
  border-top: 1px solid var(--border-color);
}
.sidebar-extra-links .sidebar-link {
  padding-left: var(--space-md);
}
.sidebar-extra-links .sidebar-link svg {
  flex-shrink: 0;
  opacity: 0.6;
}

.sidebar-footer {
  padding: var(--space-md) var(--space-lg);
  border-top: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-shrink: 0;
}

.version-badge {
  font-size: 0.7rem;
  font-weight: 600;
  color: var(--text-muted);
  background: var(--bg-tertiary);
  padding: 2px 8px;
  border-radius: var(--radius-full);
}

.footer-links {
  display: flex;
  gap: var(--space-md);
  font-size: 0.8rem;
}
.footer-links a {
  color: var(--text-muted);
}
.footer-links a:hover {
  color: var(--accent-blue);
}

/* Sidebar overlay (mobile) */
.sidebar-overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.5);
  z-index: 80;
  opacity: 0;
  transition: opacity var(--transition-normal);
}
.sidebar-overlay.active {
  opacity: 1;
}

/* =============================================
   Main Wrapper
   ============================================= */
.main-wrapper {
  margin-left: var(--sidebar-width);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  transition: margin-left var(--transition-normal);
}

/* =============================================
   Header
   ============================================= */
.header {
  position: sticky;
  top: 0;
  height: var(--header-height);
  background: var(--bg-glass);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 var(--space-xl);
  z-index: 50;
  transition: background var(--transition-normal);
}

.header-left,
.header-right {
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.menu-toggle {
  background: none;
  border: none;
  color: var(--text-primary);
  cursor: pointer;
  padding: var(--space-sm);
  border-radius: var(--radius-sm);
  transition: background var(--transition-fast);
}
.menu-toggle:hover {
  background: var(--bg-tertiary);
}

.header-center {
  flex: 1;
  display: flex;
  justify-content: center;
  max-width: 500px;
  margin: 0 auto;
}

/* Search Trigger Button */
.search-trigger {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: 8px 16px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-full);
  color: var(--text-muted);
  font-family: var(--font-body);
  font-size: 0.875rem;
  cursor: pointer;
  width: 100%;
  max-width: 400px;
  transition: all var(--transition-fast);
}
.search-trigger:hover {
  border-color: var(--text-muted);
  color: var(--text-secondary);
}
.search-trigger svg {
  flex-shrink: 0;
  opacity: 0.5;
}
.search-trigger span {
  flex: 1;
  text-align: left;
}
.search-trigger kbd {
  font-family: var(--font-body);
  font-size: 0.7rem;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  padding: 2px 6px;
  border-radius: var(--radius-sm);
  color: var(--text-muted);
  line-height: 1;
}

/* Theme Toggle */
.theme-toggle {
  background: none;
  border: none;
  color: var(--text-secondary);
  cursor: pointer;
  width: 38px;
  height: 38px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
}
.theme-toggle:hover {
  background-color: var(--bg-tertiary);
  color: var(--text-primary);
  transform: rotate(20deg);
}
.theme-toggle svg {
  transition: transform var(--transition-normal);
}

/* GitHub link in header */
.github-link {
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  padding: var(--space-sm);
  border-radius: 50%;
  transition: all var(--transition-fast);
}
.github-link:hover {
  color: var(--text-primary);
  background: var(--bg-tertiary);
}

/* =============================================
   Main Content
   ============================================= */
.main-content {
  flex: 1;
  padding: var(--space-xl) var(--space-2xl);
  max-width: 900px;
  width: 100%;
  margin: 0 auto;
}

/* Loading Spinner */
.loading-spinner {
  display: flex;
  justify-content: center;
  align-items: center;
  padding: var(--space-3xl);
}
.spinner {
  width: 40px;
  height: 40px;
  border: 3px solid var(--bg-tertiary);
  border-top-color: var(--accent-blue);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}
@keyframes spin {
  to { transform: rotate(360deg); }
}

/* =============================================
   Hero Section
   ============================================= */
.hero-section {
  text-align: center;
  padding: var(--space-3xl) 0 var(--space-2xl);
  position: relative;
}
.hero-section::before {
  content: '';
  position: absolute;
  top: -50%;
  left: 50%;
  transform: translateX(-50%);
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(88, 166, 255, 0.08) 0%, rgba(188, 140, 255, 0.04) 40%, transparent 70%);
  pointer-events: none;
  z-index: -1;
}

.hero-title {
  font-size: clamp(2.5rem, 5vw, 4rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  margin-bottom: var(--space-md);
  background: linear-gradient(135deg, var(--text-primary) 0%, var(--accent-blue) 50%, var(--accent-purple) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  animation: gradientShift 8s ease infinite;
  background-size: 200% 200%;
}
@keyframes gradientShift {
  0%, 100% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
}

.hero-subtitle {
  font-size: 1.15rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto var(--space-xl);
  line-height: 1.7;
}

/* Stats */
.stats-section {
  display: flex;
  justify-content: center;
  gap: var(--space-3xl);
}
.stat-item {
  text-align: center;
}
.stat-number {
  font-size: 2.2rem;
  font-weight: 700;
  font-family: var(--font-heading);
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.stat-label {
  font-size: 0.8rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-weight: 500;
  margin-top: var(--space-xs);
}

/* =============================================
   Category Filter Buttons
   ============================================= */
.category-filters {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
  margin: var(--space-xl) 0 var(--space-md);
}

.filter-btn {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  padding: 8px 16px;
  border-radius: var(--radius-full);
  font-family: var(--font-body);
  font-size: 0.85rem;
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}
.filter-btn:hover {
  border-color: var(--accent-blue);
  color: var(--accent-blue);
}
.filter-btn.active {
  background: var(--accent-blue);
  border-color: var(--accent-blue);
  color: #fff;
}

/* =============================================
   Topic Cards Grid
   ============================================= */
.topic-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-lg);
  margin-bottom: var(--space-3xl);
}

.topic-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  display: flex;
  flex-direction: column;
  text-decoration: none;
  color: inherit;
  position: relative;
  overflow: hidden;
  transition: all var(--transition-normal);
}
.topic-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--accent-gradient);
  opacity: 0;
  transition: opacity var(--transition-normal);
}
.topic-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg), var(--shadow-glow-blue);
  border-color: rgba(88, 166, 255, 0.3);
}
.topic-card:hover::before {
  opacity: 1;
}

.topic-card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-sm);
}

.topic-author {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 500;
}

.topic-card h3 {
  font-size: 1.05rem;
  margin-bottom: var(--space-sm);
  color: var(--text-primary);
  line-height: 1.4;
}
.topic-card p {
  font-size: 0.875rem;
  color: var(--text-secondary);
  flex: 1;
  margin-bottom: var(--space-md);
  line-height: 1.6;
}

/* Badges */
.badge {
  display: inline-block;
  padding: 3px 10px;
  border-radius: var(--radius-full);
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.badge.beginner {
  background: rgba(63, 185, 80, 0.12);
  color: var(--success);
}
.badge.intermediate {
  background: rgba(210, 153, 34, 0.12);
  color: var(--warning);
}
.badge.advanced {
  background: rgba(248, 81, 73, 0.12);
  color: var(--danger);
}

/* Tags */
.tag {
  display: inline-block;
  padding: 3px 10px;
  border-radius: var(--radius-full);
  font-size: 0.7rem;
  font-weight: 500;
  color: var(--text-muted);
  border: 1px solid var(--border-color);
  margin-top: auto;
}

/* =============================================
   Contributor Cards
   ============================================= */
.contributors-home {
  margin-bottom: var(--space-3xl);
}
.contributors-home h2 {
  font-size: 1.8rem;
  margin-bottom: var(--space-lg);
}

.contributors-section {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--space-lg);
}

.contributor-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  text-align: center;
  transition: all var(--transition-normal);
}
.contributor-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: rgba(188, 140, 255, 0.3);
}

.contributor-avatar {
  width: 72px;
  height: 72px;
  border-radius: 50%;
  margin: 0 auto var(--space-md);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.avatar-placeholder {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--accent-gradient);
  color: #fff;
  font-size: 1.5rem;
  font-weight: 700;
  font-family: var(--font-heading);
}

.contributor-name {
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: 1.1rem;
  color: var(--text-primary);
  margin-bottom: var(--space-xs);
}

.contributor-role {
  font-size: 0.85rem;
  color: var(--accent-blue);
  font-weight: 500;
  margin-bottom: var(--space-sm);
}

.contributor-bio {
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: var(--space-md);
  line-height: 1.6;
}

.contributor-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.85rem;
  color: var(--text-muted);
  transition: color var(--transition-fast);
  margin-right: 12px;
}
.contributor-link:hover {
  color: var(--accent-blue);
}

/* =============================================
   Topic Page
   ============================================= */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: 0.85rem;
  margin-bottom: var(--space-lg);
  color: var(--text-muted);
}
.breadcrumb a {
  color: var(--text-secondary);
}
.breadcrumb a:hover {
  color: var(--accent-blue);
}
.breadcrumb .separator {
  color: var(--text-muted);
  font-size: 0.8rem;
}
.breadcrumb .current {
  color: var(--text-primary);
  font-weight: 500;
}

.topic-page-header {
  margin-bottom: var(--space-xl);
  padding-bottom: var(--space-xl);
  border-bottom: 1px solid var(--border-color);
}

.topic-page-header h1 {
  font-size: clamp(1.8rem, 3vw, 2.5rem);
  margin-bottom: var(--space-md);
}

.topic-meta {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  flex-wrap: wrap;
}

.read-time {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* Topic navigation (prev/next) */
.topic-navigation {
  display: flex;
  justify-content: space-between;
  gap: var(--space-lg);
  margin-top: var(--space-3xl);
  padding-top: var(--space-xl);
  border-top: 1px solid var(--border-color);
}

.nav-prev,
.nav-next {
  display: flex;
  flex-direction: column;
  padding: var(--space-md) var(--space-lg);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  text-decoration: none;
  transition: all var(--transition-fast);
  max-width: 45%;
}
.nav-prev:hover,
.nav-next:hover {
  border-color: var(--accent-blue);
  box-shadow: var(--shadow-glow-blue);
}
.nav-next {
  text-align: right;
  margin-left: auto;
}
.nav-label {
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-xs);
}
.nav-title {
  font-weight: 600;
  color: var(--accent-blue);
  font-size: 0.9rem;
}

/* =============================================
   Article Content (Rendered Markdown)
   ============================================= */
.article-content {
  font-size: 1.05rem;
  line-height: 1.8;
}

.article-content h1 {
  font-size: 2rem;
  margin-top: var(--space-2xl);
  margin-bottom: var(--space-lg);
}
.article-content h2 {
  font-size: 1.5rem;
  margin-top: var(--space-2xl);
  margin-bottom: var(--space-md);
  padding-bottom: var(--space-sm);
  border-bottom: 1px solid var(--border-color);
}
.article-content h3 {
  font-size: 1.25rem;
  margin-top: var(--space-xl);
  margin-bottom: var(--space-md);
}
.article-content h4 {
  font-size: 1.1rem;
  margin-top: var(--space-lg);
  margin-bottom: var(--space-sm);
}

.article-content p {
  margin-bottom: var(--space-lg);
}

.heading-anchor {
  color: var(--text-muted);
  opacity: 0;
  margin-left: var(--space-sm);
  font-weight: 400;
  transition: opacity var(--transition-fast);
  text-decoration: none;
}
.article-content h1:hover .heading-anchor,
.article-content h2:hover .heading-anchor,
.article-content h3:hover .heading-anchor,
.article-content h4:hover .heading-anchor {
  opacity: 1;
}
.heading-anchor:hover {
  color: var(--accent-blue);
}

/* Lists */
.article-content ul,
.article-content ol {
  margin-bottom: var(--space-lg);
  padding-left: var(--space-xl);
}
.article-content li {
  margin-bottom: var(--space-sm);
}
.article-content li::marker {
  color: var(--accent-blue);
}

/* Blockquotes */
.article-content blockquote {
  border-left: 4px solid var(--accent-purple);
  background: var(--bg-secondary);
  padding: var(--space-md) var(--space-lg);
  margin: 0 0 var(--space-lg) 0;
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  color: var(--text-secondary);
}
.article-content blockquote p:last-child {
  margin-bottom: 0;
}

/* Tables */
.article-content table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: var(--space-lg);
  font-size: 0.9rem;
  overflow-x: auto;
  display: block;
}
.article-content th,
.article-content td {
  padding: var(--space-sm) var(--space-md);
  border: 1px solid var(--border-color);
  text-align: left;
}
.article-content th {
  background: var(--bg-tertiary);
  font-weight: 600;
}
.article-content tr:nth-child(even) {
  background: rgba(255,255,255,0.02);
}
[data-theme='light'] .article-content tr:nth-child(even) {
  background: rgba(0,0,0,0.02);
}

/* Inline Code */
.article-content code {
  font-family: var(--font-code);
  font-size: 0.88em;
  background: var(--bg-tertiary);
  padding: 0.15em 0.4em;
  border-radius: var(--radius-sm);
  color: var(--accent-purple);
  word-break: break-word;
}

/* Code Blocks */
.code-block {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  margin-bottom: var(--space-lg);
  overflow: hidden;
}
.code-block-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--space-sm) var(--space-md);
  background: var(--bg-tertiary);
  border-bottom: 1px solid var(--border-color);
  font-family: var(--font-code);
  font-size: 0.8rem;
  color: var(--text-muted);
}
.code-block-header button {
  background: none;
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  cursor: pointer;
  padding: 2px 10px;
  border-radius: var(--radius-sm);
  font-size: 0.75rem;
  font-family: var(--font-body);
  transition: all var(--transition-fast);
}
.code-block-header button:hover {
  color: var(--accent-blue);
  border-color: var(--accent-blue);
}
.code-block pre {
  margin: 0;
  padding: var(--space-md);
  overflow-x: auto;
}
.code-block pre code {
  background: none;
  padding: 0;
  color: var(--text-primary);
  font-size: 0.875rem;
  line-height: 1.6;
}

/* Horizontal Rule */
.article-content hr {
  border: none;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--border-color), var(--accent-blue), var(--border-color), transparent);
  margin: var(--space-2xl) 0;
}

/* Images */
.article-content img {
  max-width: 100%;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
}

/* =============================================
   Coming Soon Placeholder
   ============================================= */
.coming-soon {
  text-align: center;
  padding: var(--space-3xl) var(--space-xl);
  border: 2px dashed var(--border-color);
  border-radius: var(--radius-lg);
  margin: var(--space-xl) 0;
}
.coming-soon-icon {
  font-size: 3rem;
  margin-bottom: var(--space-md);
}
.coming-soon h2 {
  margin-bottom: var(--space-md);
  color: var(--text-primary);
}
.coming-soon p {
  color: var(--text-secondary);
  margin-bottom: var(--space-sm);
}
.coming-soon-desc {
  font-style: italic;
  color: var(--text-muted);
}
.coming-soon-link {
  display: inline-block;
  margin-top: var(--space-lg);
  padding: 8px 20px;
  border: 1px solid var(--accent-blue);
  border-radius: var(--radius-full);
  color: var(--accent-blue);
  font-weight: 500;
  transition: all var(--transition-fast);
}
.coming-soon-link:hover {
  background: var(--accent-blue);
  color: #fff;
}

/* =============================================
   Table of Contents (Right Sidebar)
   ============================================= */
.toc {
  position: fixed;
  right: var(--space-xl);
  top: calc(var(--header-height) + var(--space-2xl));
  width: var(--toc-width);
  max-height: calc(100vh - var(--header-height) - 100px);
  overflow-y: auto;
  display: none;
}

.toc-header h3 {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: var(--space-md);
  font-weight: 600;
}

.toc-nav {
  border-left: 2px solid var(--border-color);
  padding-left: 0;
}

.toc-link {
  display: block;
  padding: 4px 0 4px var(--space-md);
  font-size: 0.8rem;
  color: var(--text-muted);
  text-decoration: none;
  border-left: 2px solid transparent;
  margin-left: -2px;
  transition: all var(--transition-fast);
  line-height: 1.5;
}
.toc-link:hover {
  color: var(--text-secondary);
}
.toc-link.active {
  color: var(--accent-blue);
  border-left-color: var(--accent-blue);
}
.toc-link.toc-indent {
  padding-left: calc(var(--space-md) + 12px);
  font-size: 0.78rem;
}

@media (min-width: 1500px) {
  .toc {
    display: block;
  }
  .main-wrapper {
    padding-right: calc(var(--toc-width) + var(--space-xl));
  }
}

/* =============================================
   Search Overlay
   ============================================= */
.search-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  z-index: 1000;
  display: flex;
  justify-content: center;
  align-items: flex-start;
  padding-top: 15vh;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-normal);
}
.search-overlay.active {
  opacity: 1;
  visibility: visible;
}

.search-modal {
  width: 90%;
  max-width: 560px;
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  overflow: hidden;
  transform: translateY(-20px) scale(0.98);
  transition: transform var(--transition-normal);
}
.search-overlay.active .search-modal {
  transform: translateY(0) scale(1);
}

.search-input-wrapper {
  display: flex;
  align-items: center;
  padding: var(--space-md) var(--space-lg);
  gap: var(--space-md);
  border-bottom: 1px solid var(--border-color);
}
.search-input-wrapper svg {
  flex-shrink: 0;
  color: var(--text-muted);
}

.search-input-wrapper input,
#searchInput {
  flex: 1;
  border: none;
  background: transparent;
  color: var(--text-primary);
  font-family: var(--font-body);
  font-size: 1.1rem;
  outline: none;
}
#searchInput::placeholder {
  color: var(--text-muted);
}

.search-results {
  max-height: 400px;
  overflow-y: auto;
  padding: var(--space-sm) 0;
}

.search-empty {
  padding: var(--space-xl);
  text-align: center;
  color: var(--text-muted);
  font-size: 0.9rem;
}

.search-result-item {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: var(--space-sm) var(--space-lg);
  text-decoration: none;
  color: inherit;
  transition: background var(--transition-fast);
  cursor: pointer;
}
.search-result-item:hover,
.search-result-item.selected {
  background: var(--bg-secondary);
}

.search-result-icon {
  font-size: 1.2rem;
  flex-shrink: 0;
  width: 32px;
  text-align: center;
}

.search-result-info {
  flex: 1;
  min-width: 0;
}

.search-result-title {
  font-weight: 500;
  color: var(--text-primary);
  font-size: 0.9rem;
}

.search-result-meta {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 2px;
}

.search-footer {
  padding: var(--space-sm) var(--space-lg);
  border-top: 1px solid var(--border-color);
  text-align: center;
}

.search-hint {
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* =============================================
   Back to Top Button
   ============================================= */
.back-to-top {
  position: fixed;
  bottom: var(--space-xl);
  right: var(--space-xl);
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--bg-secondary);
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: all var(--transition-normal);
  z-index: 99;
}
.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.back-to-top:hover {
  background: var(--accent-blue);
  color: #fff;
  border-color: var(--accent-blue);
  transform: translateY(-3px);
  box-shadow: var(--shadow-glow-blue);
}

/* =============================================
   Scroll Animations
   ============================================= */
.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* =============================================
   Noscript
   ============================================= */
.noscript-message {
  text-align: center;
  padding: var(--space-2xl);
  background: var(--bg-secondary);
  color: var(--text-primary);
  font-size: 1.1rem;
}

/* =============================================
   Responsive Design
   ============================================= */
@media (max-width: 1024px) {
  .main-content {
    padding: var(--space-lg);
  }
  .stats-section {
    gap: var(--space-xl);
  }
}

/* Desktop Sidebar Toggle */
@media (min-width: 769px) {
  body.sidebar-collapsed .sidebar {
    transform: translateX(-100%);
  }
  body.sidebar-collapsed .main-wrapper {
    margin-left: 0;
  }
}

@media (max-width: 768px) {

  .sidebar {
    transform: translateX(-100%);
    width: 280px;
    box-shadow: none;
    z-index: 100;
  }
  .sidebar.open {
    transform: translateX(0);
    box-shadow: var(--shadow-lg);
  }

  .sidebar-overlay {
    display: block;
  }

  .main-wrapper {
    margin-left: 0;
  }

  .header {
    padding: 0 var(--space-md);
  }

  .search-trigger span {
    display: none;
  }
  .search-trigger kbd {
    display: none;
  }

  .main-content {
    padding: var(--space-md);
  }

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

  .stats-section {
    gap: var(--space-lg);
  }
  .stat-number {
    font-size: 1.6rem;
  }

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

  .topic-navigation {
    flex-direction: column;
  }
  .nav-prev,
  .nav-next {
    max-width: 100%;
  }
}

@media (max-width: 480px) {
  .stats-section {
    flex-direction: column;
    gap: var(--space-md);
  }
  .category-filters {
    justify-content: center;
  }
}

/* =============================================
   Print Styles
   ============================================= */
@media print {
  body {
    background: #fff;
    color: #000;
  }
  .sidebar,
  .header,
  .back-to-top,
  .theme-toggle,
  .toc,
  .progress-bar,
  .search-overlay,
  .sidebar-overlay,
  .menu-toggle,
  .topic-navigation {
    display: none !important;
  }
  .main-wrapper {
    margin: 0;
  }
  .main-content {
    margin: 0;
    padding: 0;
    max-width: none;
  }
  .article-content a::after {
    content: " (" attr(href) ")";
    font-size: 0.8em;
    color: #666;
  }
  .code-block {
    border: 1px solid #ccc;
    page-break-inside: avoid;
  }
}

/* =============================================
   Crazy About Page IDE Styles
   ============================================= */
.about-ide-window {
  background-color: #0d1117;
  border: 1px solid #30363d;
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 12px 24px rgba(0,0,0,0.5);
  margin-top: 2rem;
  font-family: var(--font-code);
}
.ide-header {
  background-color: #161b22;
  border-bottom: 1px solid #30363d;
  padding: 10px 16px;
  display: flex;
  align-items: center;
  position: relative;
}
.ide-dots {
  display: flex;
  gap: 6px;
}
.ide-dots .dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
}
.dot.red { background-color: #ff5f56; }
.dot.yellow { background-color: #ffbd2e; }
.dot.green { background-color: #27c93f; }

.ide-filename {
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
  color: #8b949e;
  font-size: 0.85rem;
  font-weight: 500;
  font-family: var(--font-body);
}
.ide-content {
  padding: 0;
}
.ide-content pre {
  margin: 0;
  border: none;
  border-radius: 0;
  background-color: transparent !important;
  font-size: 0.95rem;
  line-height: 1.5;
}

/* =============================================
   Feature: Godbolt Integration
   ============================================= */
.godbolt-wrapper {
  width: 100%;
  height: 600px;
  border-radius: var(--radius-md);
  overflow: hidden;
  margin: var(--space-lg) 0;
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-sm);
  background: var(--bg-secondary);
}
.godbolt-wrapper iframe {
  width: 100%;
  height: 100%;
  border: none;
}