/* ============================================================
   LearningHub Main CSS
   ============================================================ */

/* Custom Properties */
:root {
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-primary-light: #dbeafe;
  --color-secondary: #7c3aed;
  --color-secondary-light: #ede9fe;
  --color-accent: #059669;
  --color-accent-light: #d1fae5;
  --color-background: #ffffff;
  --color-surface: #f8fafc;
  --color-surface-2: #f1f5f9;
  --color-text: #1e293b;
  --color-text-muted: #64748b;
  --color-border: #e2e8f0;
  --color-border-dark: #cbd5e1;

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;

  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 1.875rem;
  --text-4xl: 2.25rem;
  --text-5xl: 3rem;

  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;

  --radius-sm: 0.25rem;
  --radius: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-full: 9999px;

  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow: 0 1px 3px rgba(0,0,0,0.1), 0 1px 2px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.07), 0 2px 4px rgba(0,0,0,0.06);
  --shadow-lg: 0 10px 15px rgba(0,0,0,0.1), 0 4px 6px rgba(0,0,0,0.05);
  --shadow-xl: 0 20px 25px rgba(0,0,0,0.1), 0 10px 10px rgba(0,0,0,0.04);

  --max-width: 1100px;
  --header-height: 64px;
  --transition: 0.2s ease;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-background);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img, picture, video, canvas, svg {
  display: block;
  max-width: 100%;
}

input, button, textarea, select {
  font: inherit;
}

p, h1, h2, h3, h4, h5, h6 {
  overflow-wrap: break-word;
}

a {
  color: var(--color-primary);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

ul, ol {
  list-style: none;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ============================================================
   Layout
   ============================================================ */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-6);
}

main {
  min-height: calc(100vh - var(--header-height) - 300px);
}

/* ============================================================
   Typography
   ============================================================ */
h1 { font-size: clamp(var(--text-3xl), 5vw, var(--text-5xl)); font-weight: 800; line-height: 1.1; letter-spacing: -0.02em; }
h2 { font-size: clamp(var(--text-2xl), 4vw, var(--text-4xl)); font-weight: 700; line-height: 1.2; letter-spacing: -0.01em; }
h3 { font-size: clamp(var(--text-xl), 3vw, var(--text-2xl)); font-weight: 600; line-height: 1.3; }
h4 { font-size: var(--text-xl); font-weight: 600; }
h5 { font-size: var(--text-lg); font-weight: 600; }
h6 { font-size: var(--text-base); font-weight: 600; }

/* ============================================================
   Buttons
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-6);
  border-radius: var(--radius);
  font-size: var(--text-sm);
  font-weight: 600;
  cursor: pointer;
  border: 2px solid transparent;
  transition: all var(--transition);
  text-decoration: none;
  white-space: nowrap;
}

.btn:hover { text-decoration: none; }

.btn-primary {
  background-color: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
}
.btn-primary:hover { background-color: var(--color-primary-dark); border-color: var(--color-primary-dark); color: #fff; }

.btn-outline {
  background-color: transparent;
  color: var(--color-primary);
  border-color: var(--color-primary);
}
.btn-outline:hover { background-color: var(--color-primary); color: #fff; }

.btn-white {
  background-color: #fff;
  color: var(--color-primary);
  border-color: #fff;
}
.btn-white:hover { background-color: var(--color-primary-light); }

.btn-outline-white {
  background-color: transparent;
  color: #fff;
  border-color: rgba(255,255,255,0.7);
}
.btn-outline-white:hover { background-color: rgba(255,255,255,0.15); color: #fff; }

.btn-sm {
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-xs);
}

/* ============================================================
   Badges
   ============================================================ */
.category-badge {
  display: inline-flex;
  align-items: center;
  padding: var(--space-1) var(--space-3);
  background-color: var(--color-primary-light);
  color: var(--color-primary);
  border-radius: var(--radius-full);
  font-size: var(--text-xs);
  font-weight: 600;
  text-decoration: none;
  transition: all var(--transition);
}
.category-badge:hover { background-color: var(--color-primary); color: #fff; text-decoration: none; }
.category-badge--hero { background-color: rgba(255,255,255,0.25); color: #fff; margin-bottom: var(--space-4); }
.category-badge--hero:hover { background-color: rgba(255,255,255,0.4); color: #fff; }

.tag-badge {
  display: inline-flex;
  align-items: center;
  padding: var(--space-1) var(--space-3);
  background-color: var(--color-surface-2);
  color: var(--color-text-muted);
  border-radius: var(--radius-full);
  font-size: var(--text-xs);
  font-weight: 500;
  text-decoration: none;
  transition: all var(--transition);
}
.tag-badge:hover { background-color: var(--color-secondary-light); color: var(--color-secondary); text-decoration: none; }
.tag-badge--hero { background-color: rgba(255,255,255,0.2); color: #fff; font-size: var(--text-sm); }

/* ============================================================
   Header
   ============================================================ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: #fff;
  border-bottom: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
  height: var(--header-height);
}

.header-inner {
  display: flex;
  align-items: center;
  gap: var(--space-6);
  height: var(--header-height);
}

.logo {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  text-decoration: none;
  flex-shrink: 0;
}
.logo-icon { font-size: 1.5rem; }
.logo-text {
  font-size: var(--text-lg);
  font-weight: 800;
  color: var(--color-text);
  letter-spacing: -0.01em;
}
.logo:hover { text-decoration: none; }
.logo:hover .logo-text { color: var(--color-primary); }

.main-nav { flex: 1; }
.nav-list { display: flex; align-items: center; gap: var(--space-1); list-style: none; }
.nav-link {
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius);
  color: var(--color-text-muted);
  font-size: var(--text-sm);
  font-weight: 500;
  text-decoration: none;
  transition: all var(--transition);
  white-space: nowrap;
}
.nav-link:hover { color: var(--color-primary); background-color: var(--color-primary-light); text-decoration: none; }
.nav-link.active { color: var(--color-primary); background-color: var(--color-primary-light); }

/* Header Search */
.header-search { position: relative; flex-shrink: 0; }
.search-form-header {
  display: flex;
  align-items: center;
  position: relative;
}
.search-form-header input {
  padding: var(--space-2) var(--space-3);
  padding-right: var(--space-10);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  font-size: var(--text-sm);
  width: 200px;
  background-color: var(--color-surface);
  transition: all var(--transition);
  outline: none;
}
.search-form-header input:focus {
  border-color: var(--color-primary);
  background-color: #fff;
  box-shadow: 0 0 0 3px var(--color-primary-light);
  width: 260px;
}
.search-form-header button {
  position: absolute;
  right: var(--space-3);
  background: none;
  border: none;
  cursor: pointer;
  color: var(--color-text-muted);
  display: flex;
  align-items: center;
  padding: 0;
}
.search-form-header button:hover { color: var(--color-primary); }

/* Search dropdown */
.search-dropdown {
  position: absolute;
  top: calc(100% + var(--space-2));
  left: 0;
  right: 0;
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-xl);
  max-height: 400px;
  overflow-y: auto;
  z-index: 200;
  display: none;
}
.search-dropdown.active { display: block; }
.search-result-item {
  display: block;
  padding: var(--space-3) var(--space-4);
  border-bottom: 1px solid var(--color-border);
  text-decoration: none;
  color: var(--color-text);
  transition: background var(--transition);
}
.search-result-item:last-child { border-bottom: none; }
.search-result-item:hover { background-color: var(--color-surface); text-decoration: none; }
.search-result-item .result-title { font-weight: 600; font-size: var(--text-sm); }
.search-result-item .result-excerpt { font-size: var(--text-xs); color: var(--color-text-muted); margin-top: var(--space-1); }
.search-result-item .result-category { font-size: var(--text-xs); color: var(--color-primary); font-weight: 600; }
.search-no-results {
  padding: var(--space-4);
  text-align: center;
  color: var(--color-text-muted);
  font-size: var(--text-sm);
}
mark { background-color: #fef08a; border-radius: 2px; padding: 0 2px; }

/* Hamburger */
.hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  padding: var(--space-2);
  background: none;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  cursor: pointer;
  width: 40px;
  height: 40px;
  flex-shrink: 0;
}
.hamburger span {
  display: block;
  width: 18px;
  height: 2px;
  background-color: var(--color-text);
  border-radius: 2px;
  transition: all var(--transition);
}
.hamburger.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.hamburger.open span:nth-child(2) { opacity: 0; }
.hamburger.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* Mobile nav */
.mobile-nav {
  background: #fff;
  border-top: 1px solid var(--color-border);
  padding: var(--space-4) 0;
}
.mobile-nav-list { list-style: none; }
.mobile-nav-link {
  display: block;
  padding: var(--space-3) var(--space-6);
  color: var(--color-text);
  font-weight: 500;
  text-decoration: none;
  transition: all var(--transition);
}
.mobile-nav-link:hover { color: var(--color-primary); background-color: var(--color-surface); }
.mobile-nav-link.active { color: var(--color-primary); }

/* ============================================================
   Hero Section
   ============================================================ */
.hero {
  background: linear-gradient(135deg, #1e3a5f 0%, #2563eb 50%, #7c3aed 100%);
  color: #fff;
  padding: var(--space-24) 0;
  text-align: center;
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse at 60% 50%, rgba(124,58,237,0.4) 0%, transparent 70%);
}
.hero-content { position: relative; max-width: 700px; margin: 0 auto; }
.hero-title { font-size: clamp(2.5rem, 6vw, 4rem); font-weight: 900; line-height: 1.05; margin-bottom: var(--space-5); color: #fff; }
.hero-highlight { color: #fbbf24; }
.hero-subtitle { font-size: var(--text-xl); color: rgba(255,255,255,0.85); line-height: 1.5; margin-bottom: var(--space-8); }

/* Hero search */
.hero-search-form {
  display: flex;
  gap: var(--space-2);
  max-width: 520px;
  margin: 0 auto var(--space-10);
}
.hero-search-form input {
  flex: 1;
  padding: var(--space-4) var(--space-5);
  border: none;
  border-radius: var(--radius);
  font-size: var(--text-base);
  outline: none;
  box-shadow: var(--shadow-lg);
}
.hero-search-form input:focus { box-shadow: 0 0 0 3px rgba(255,255,255,0.3), var(--shadow-lg); }
.hero-search-form .btn { padding: var(--space-4) var(--space-6); flex-shrink: 0; }

/* Hero stats */
.hero-stats {
  display: flex;
  justify-content: center;
  gap: var(--space-10);
  flex-wrap: wrap;
}
.hero-stat { text-align: center; }
.hero-stat-number { display: block; font-size: var(--text-3xl); font-weight: 800; color: #fbbf24; }
.hero-stat-label { font-size: var(--text-sm); color: rgba(255,255,255,0.75); }

/* ============================================================
   Section Styles
   ============================================================ */
.featured-section,
.categories-section,
.recent-section,
.home-cta-section {
  padding: var(--space-20) 0;
}

.categories-section,
.home-cta-section {
  background-color: var(--color-surface);
}

.section-title {
  font-size: clamp(var(--text-2xl), 4vw, var(--text-3xl));
  font-weight: 800;
  color: var(--color-text);
  margin-bottom: var(--space-2);
}

.section-subtitle {
  color: var(--color-text-muted);
  font-size: var(--text-lg);
  margin-bottom: var(--space-10);
}

.section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-8);
}

.view-all-link {
  font-weight: 600;
  color: var(--color-primary);
  font-size: var(--text-sm);
}

/* ============================================================
   Featured Articles Grid
   ============================================================ */
.featured-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-6);
}

.featured-card {
  background: #fff;
  border-radius: var(--radius-xl);
  overflow: hidden;
  box-shadow: var(--shadow-md);
  transition: transform var(--transition), box-shadow var(--transition);
  display: flex;
  flex-direction: column;
}
.featured-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-xl); }

.featured-card-image {
  height: 160px;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
}
.featured-card-icon { font-size: 3rem; }
.featured-badge {
  position: absolute;
  top: var(--space-3);
  right: var(--space-3);
  background-color: #fbbf24;
  color: #1e293b;
  padding: 2px var(--space-3);
  border-radius: var(--radius-full);
  font-size: var(--text-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.featured-card-body {
  padding: var(--space-6);
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}
.featured-card-title { font-size: var(--text-xl); font-weight: 700; line-height: 1.3; }
.featured-card-title a { color: var(--color-text); text-decoration: none; }
.featured-card-title a:hover { color: var(--color-primary); }
.featured-card-desc { color: var(--color-text-muted); font-size: var(--text-sm); line-height: 1.6; flex: 1; }
.featured-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: auto;
}
.article-date { font-size: var(--text-xs); color: var(--color-text-muted); }

/* ============================================================
   Categories Grid
   ============================================================ */
.categories-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-5);
}

.category-card {
  background: #fff;
  border-radius: var(--radius-xl);
  padding: var(--space-6);
  text-decoration: none;
  border: 1px solid var(--color-border);
  transition: all var(--transition);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}
.category-card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
  text-decoration: none;
}

.category-card-icon {
  width: 52px;
  height: 52px;
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
}
.category-card-name { font-size: var(--text-lg); font-weight: 700; color: var(--color-text); }
.category-card-desc { font-size: var(--text-sm); color: var(--color-text-muted); line-height: 1.5; flex: 1; }
.category-card-link { font-size: var(--text-sm); font-weight: 600; color: var(--color-primary); margin-top: auto; }

/* ============================================================
   Article Grid
   ============================================================ */
.article-grid { display: grid; gap: var(--space-6); }
.article-grid--3 { grid-template-columns: repeat(3, 1fr); }
.article-grid--2 { grid-template-columns: repeat(2, 1fr); }

/* ============================================================
   Article Cards
   ============================================================ */
.article-card {
  background: #fff;
  border-radius: var(--radius-xl);
  overflow: hidden;
  border: 1px solid var(--color-border);
  transition: all var(--transition);
  display: flex;
  flex-direction: column;
}
.article-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
  border-color: var(--color-primary-light);
}

.article-card-image {
  height: 120px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2.5rem;
}
.article-card-link { text-decoration: none; }

.article-card-body {
  padding: var(--space-5);
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}
.article-card-meta {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}
.reading-time { font-size: var(--text-xs); color: var(--color-text-muted); }
.article-card-title { font-size: var(--text-lg); font-weight: 700; line-height: 1.3; }
.article-card-title a { color: var(--color-text); text-decoration: none; }
.article-card-title a:hover { color: var(--color-primary); }
.article-card-excerpt { font-size: var(--text-sm); color: var(--color-text-muted); line-height: 1.6; flex: 1; }
.article-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: auto;
  padding-top: var(--space-3);
  border-top: 1px solid var(--color-border);
}
.read-more { font-size: var(--text-sm); font-weight: 600; color: var(--color-primary); text-decoration: none; }
.read-more:hover { text-decoration: underline; }

/* ============================================================
   Home CTA Section
   ============================================================ */
.home-cta {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-12);
  align-items: center;
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  border-radius: var(--radius-xl);
  padding: var(--space-12);
  color: #fff;
}
.home-cta h2 { font-size: var(--text-3xl); margin-bottom: var(--space-4); color: #fff; }
.home-cta p { color: rgba(255,255,255,0.85); line-height: 1.6; margin-bottom: var(--space-6); }
.home-cta-buttons { display: flex; gap: var(--space-4); flex-wrap: wrap; }

.cta-visual-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-4);
}
.cta-visual-card {
  background: rgba(255,255,255,0.15);
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255,255,255,0.25);
  border-radius: var(--radius-lg);
  padding: var(--space-5);
  font-weight: 600;
  font-size: var(--text-sm);
  color: #fff;
  text-align: center;
}

/* ============================================================
   Article Page
   ============================================================ */
.breadcrumbs { padding: var(--space-4) 0; }
.breadcrumb-list {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  list-style: none;
  flex-wrap: wrap;
}
.breadcrumb-list li:not(:last-child)::after {
  content: '›';
  margin-left: var(--space-2);
  color: var(--color-text-muted);
}
.breadcrumb-list a { color: var(--color-text-muted); font-size: var(--text-sm); text-decoration: none; }
.breadcrumb-list a:hover { color: var(--color-primary); }
.breadcrumb-list li:last-child { color: var(--color-text); font-size: var(--text-sm); font-weight: 500; }

.article-hero {
  padding: var(--space-16) 0;
  color: #fff;
}
.article-hero-title {
  font-size: clamp(1.75rem, 4vw, 2.75rem);
  font-weight: 800;
  line-height: 1.15;
  margin-bottom: var(--space-5);
  color: #fff;
  max-width: 700px;
}
.article-hero-meta {
  display: flex;
  align-items: center;
  gap: var(--space-5);
  flex-wrap: wrap;
}
.article-hero-meta span { font-size: var(--text-sm); opacity: 0.9; }
.article-author::before { content: '✍️ '; }
.article-date::before { content: '📅 '; }
.article-reading-time::before { content: '⏱️ '; }

.article-layout {
  display: grid;
  grid-template-columns: 1fr 280px;
  gap: var(--space-10);
  padding: var(--space-10) 0;
  align-items: start;
}

/* Prose styles */
.prose {
  max-width: 65ch;
  color: var(--color-text);
  line-height: 1.8;
}
.prose h2 {
  font-size: var(--text-2xl);
  font-weight: 700;
  margin-top: var(--space-10);
  margin-bottom: var(--space-4);
  color: var(--color-text);
  padding-bottom: var(--space-2);
  border-bottom: 2px solid var(--color-border);
}
.prose h3 {
  font-size: var(--text-xl);
  font-weight: 600;
  margin-top: var(--space-8);
  margin-bottom: var(--space-3);
  color: var(--color-text);
}
.prose h4 {
  font-size: var(--text-lg);
  font-weight: 600;
  margin-top: var(--space-6);
  margin-bottom: var(--space-2);
}
.prose p { margin-bottom: var(--space-5); }
.prose ul, .prose ol {
  margin-bottom: var(--space-5);
  padding-left: var(--space-6);
}
.prose ul { list-style: disc; }
.prose ol { list-style: decimal; }
.prose li { margin-bottom: var(--space-2); }
.prose a { color: var(--color-primary); text-decoration: underline; }
.prose a:hover { color: var(--color-primary-dark); }
.prose strong { font-weight: 700; }
.prose em { font-style: italic; }
.prose blockquote {
  border-left: 4px solid var(--color-primary);
  padding-left: var(--space-5);
  margin: var(--space-6) 0;
  color: var(--color-text-muted);
  font-style: italic;
}
.prose code {
  background-color: var(--color-surface-2);
  padding: 2px 6px;
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.875em;
}
.prose pre {
  background-color: var(--color-text);
  color: #f8fafc;
  padding: var(--space-5);
  border-radius: var(--radius-lg);
  overflow-x: auto;
  margin-bottom: var(--space-6);
}
.prose pre code { background: none; padding: 0; font-size: var(--text-sm); }
.prose hr { border: none; border-top: 2px solid var(--color-border); margin: var(--space-8) 0; }
.prose table { width: 100%; border-collapse: collapse; margin-bottom: var(--space-6); }
.prose th, .prose td { padding: var(--space-3) var(--space-4); border: 1px solid var(--color-border); text-align: left; }
.prose th { background-color: var(--color-surface); font-weight: 600; }

/* Article Tags */
.article-tags {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  flex-wrap: wrap;
  margin-top: var(--space-8);
  padding-top: var(--space-6);
  border-top: 1px solid var(--color-border);
}
.tags-label { font-size: var(--text-sm); font-weight: 600; color: var(--color-text-muted); }

/* CTA Block */
.cta-block {
  display: flex;
  align-items: center;
  gap: var(--space-5);
  background: linear-gradient(135deg, var(--color-primary-light), var(--color-secondary-light));
  border: 1px solid var(--color-primary-light);
  border-radius: var(--radius-xl);
  padding: var(--space-6);
  margin-top: var(--space-8);
}
.cta-icon { font-size: 2.5rem; flex-shrink: 0; }
.cta-text { font-size: var(--text-base); font-weight: 600; color: var(--color-text); margin-bottom: var(--space-3); }
.cta-button {
  display: inline-flex;
  align-items: center;
  padding: var(--space-2) var(--space-5);
  background-color: var(--color-primary);
  color: #fff;
  border-radius: var(--radius);
  font-size: var(--text-sm);
  font-weight: 600;
  text-decoration: none;
  transition: all var(--transition);
}
.cta-button:hover { background-color: var(--color-primary-dark); color: #fff; text-decoration: none; }

/* Sidebar */
.article-sidebar {
  position: sticky;
  top: calc(var(--header-height) + var(--space-6));
  display: flex;
  flex-direction: column;
  gap: var(--space-5);
}
.sidebar-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-5);
}
.sidebar-heading {
  font-size: var(--text-base);
  font-weight: 700;
  margin-bottom: var(--space-4);
  color: var(--color-text);
}
.sidebar-newsletter p { font-size: var(--text-sm); color: var(--color-text-muted); margin-bottom: var(--space-4); }

/* TOC */
.toc-list { list-style: none; padding: 0; }
.toc-item { margin-bottom: var(--space-2); }
.toc-item a {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  text-decoration: none;
  transition: color var(--transition);
}
.toc-item a:hover { color: var(--color-primary); }
.toc-h3 { padding-left: var(--space-4); }

/* Related Articles */
.related-articles {
  padding: var(--space-10) 0 var(--space-16);
  border-top: 1px solid var(--color-border);
}
.related-articles .section-title { margin-bottom: var(--space-6); }

/* ============================================================
   Category & Tag Pages
   ============================================================ */
.category-hero, .tag-hero {
  background: linear-gradient(135deg, var(--color-surface), var(--color-surface-2));
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-12) 0;
}
.category-hero-title, .tag-hero-title {
  font-size: clamp(var(--text-2xl), 5vw, var(--text-4xl));
  font-weight: 800;
  margin-bottom: var(--space-3);
}
.category-hero-desc { color: var(--color-text-muted); font-size: var(--text-lg); margin-bottom: var(--space-4); max-width: 600px; }
.category-count {
  display: inline-block;
  padding: var(--space-1) var(--space-4);
  background: var(--color-primary-light);
  color: var(--color-primary);
  border-radius: var(--radius-full);
  font-size: var(--text-sm);
  font-weight: 600;
}

.category-page .container { padding-top: var(--space-10); padding-bottom: var(--space-16); }
.tag-page .container { padding-top: var(--space-10); padding-bottom: var(--space-16); }

/* ============================================================
   Page Hero (generic)
   ============================================================ */
.page-hero {
  background: linear-gradient(135deg, var(--color-surface), var(--color-surface-2));
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-12) 0;
}
.page-hero h1 { margin-bottom: var(--space-3); }
.page-hero-subtitle { color: var(--color-text-muted); font-size: var(--text-lg); }

.page-prose {
  padding: var(--space-12) 0;
  max-width: none;
}
.page-prose h2 { margin-top: var(--space-10); }

/* Team Grid */
.team-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-5);
  margin: var(--space-6) 0;
}
.team-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-5);
}
.team-avatar {
  width: 52px;
  height: 52px;
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-weight: 700;
  font-size: var(--text-lg);
  margin-bottom: var(--space-3);
}
.team-card h3 { font-size: var(--text-lg); margin-bottom: var(--space-2); }
.team-card p { font-size: var(--text-sm); color: var(--color-text-muted); }

/* ============================================================
   Categories List Page
   ============================================================ */
.categories-list { padding: var(--space-10) 0 var(--space-16); display: flex; flex-direction: column; gap: var(--space-12); }
.category-section {}
.category-section-header {
  display: flex;
  align-items: flex-start;
  gap: var(--space-5);
  padding-left: var(--space-4);
  border-left: 4px solid;
  margin-bottom: var(--space-6);
}
.category-section-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  flex-shrink: 0;
}
.category-section-name { font-size: var(--text-2xl); font-weight: 800; }
.category-section-name a { color: var(--color-text); text-decoration: none; }
.category-section-name a:hover { color: var(--color-primary); }
.category-section-desc { font-size: var(--text-base); color: var(--color-text-muted); margin-top: var(--space-2); }
.category-section-link { margin-left: auto; flex-shrink: 0; align-self: center; }

/* ============================================================
   Search Page
   ============================================================ */
.search-page .container { padding-top: var(--space-8); padding-bottom: var(--space-16); }
.search-main { max-width: 800px; margin: 0 auto; }

.search-page-form { margin-bottom: var(--space-6); }
.search-input-wrap {
  position: relative;
  display: flex;
  align-items: center;
}
.search-icon {
  position: absolute;
  left: var(--space-4);
  color: var(--color-text-muted);
  pointer-events: none;
}
#search-page-input {
  width: 100%;
  padding: var(--space-4) var(--space-5) var(--space-4) var(--space-12);
  border: 2px solid var(--color-border);
  border-radius: var(--radius-lg);
  font-size: var(--text-lg);
  outline: none;
  background: #fff;
  transition: border-color var(--transition), box-shadow var(--transition);
}
#search-page-input:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px var(--color-primary-light);
}
.search-clear {
  position: absolute;
  right: var(--space-4);
  background: none;
  border: none;
  cursor: pointer;
  font-size: var(--text-lg);
  color: var(--color-text-muted);
  line-height: 1;
  padding: var(--space-1);
}
.search-clear:hover { color: var(--color-text); }

.search-filters { display: flex; align-items: center; gap: var(--space-3); flex-wrap: wrap; margin-bottom: var(--space-6); }
.filter-label { font-size: var(--text-sm); font-weight: 600; color: var(--color-text-muted); }
.filter-buttons { display: flex; gap: var(--space-2); flex-wrap: wrap; }
.filter-btn {
  padding: var(--space-1) var(--space-3);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  background: #fff;
  color: var(--color-text-muted);
  font-size: var(--text-xs);
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
}
.filter-btn:hover { border-color: var(--color-primary); color: var(--color-primary); }
.filter-btn.active { background: var(--color-primary); border-color: var(--color-primary); color: #fff; }

.search-status {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  margin-bottom: var(--space-4);
  min-height: 1.5em;
}

.search-results-grid { margin-bottom: var(--space-8); }

.search-initial { padding: var(--space-6) 0; }
.search-initial-title { font-size: var(--text-xl); font-weight: 700; margin-bottom: var(--space-5); }
.tag-cloud { display: flex; flex-wrap: wrap; gap: var(--space-3); }

/* Empty State */
.empty-state {
  text-align: center;
  padding: var(--space-16) 0;
  color: var(--color-text-muted);
}
.empty-state p { font-size: var(--text-lg); margin-bottom: var(--space-6); }

/* ============================================================
   Footer
   ============================================================ */
.site-footer {
  background-color: var(--color-text);
  color: rgba(255,255,255,0.8);
  padding: var(--space-16) 0 var(--space-8);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1fr;
  gap: var(--space-10);
  margin-bottom: var(--space-10);
}

.footer-brand .footer-logo {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  text-decoration: none;
  margin-bottom: var(--space-4);
}
.footer-brand .logo-text { color: #fff; font-size: var(--text-lg); font-weight: 800; }
.footer-tagline { font-size: var(--text-sm); line-height: 1.6; color: rgba(255,255,255,0.65); margin-bottom: var(--space-5); }
.footer-social { display: flex; gap: var(--space-3); }
.footer-social a { color: rgba(255,255,255,0.6); transition: color var(--transition); }
.footer-social a:hover { color: #fff; }

.footer-heading { font-size: var(--text-sm); font-weight: 700; color: #fff; text-transform: uppercase; letter-spacing: 0.05em; margin-bottom: var(--space-4); }
.footer-links ul { list-style: none; display: flex; flex-direction: column; gap: var(--space-2); }
.footer-links a { font-size: var(--text-sm); color: rgba(255,255,255,0.65); text-decoration: none; transition: color var(--transition); }
.footer-links a:hover { color: #fff; }

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: var(--space-8);
  border-top: 1px solid rgba(255,255,255,0.1);
  font-size: var(--text-sm);
  color: rgba(255,255,255,0.5);
}
.footer-bottom a { color: rgba(255,255,255,0.65); }
.footer-bottom a:hover { color: #fff; }

/* ============================================================
   Breadcrumbs in article hero
   ============================================================ */
.article-page .breadcrumbs .breadcrumb-list a { color: rgba(255,255,255,0.7); }
.article-page .breadcrumbs .breadcrumb-list a:hover { color: #fff; }
.article-page .breadcrumbs .breadcrumb-list li:last-child { color: rgba(255,255,255,0.9); }
.article-page .breadcrumbs .breadcrumb-list li:not(:last-child)::after { color: rgba(255,255,255,0.5); }
.article-page .breadcrumbs { padding: var(--space-4) 0 0; }

/* ============================================================
   Responsive: 768px
   ============================================================ */
@media (max-width: 768px) {
  .main-nav { display: none; }
  .header-search { display: none; }
  .hamburger { display: flex; }

  .hero { padding: var(--space-16) 0; }
  .hero-search-form { flex-direction: column; }
  .hero-stats { gap: var(--space-6); }

  .featured-grid { grid-template-columns: 1fr; }
  .categories-grid { grid-template-columns: repeat(2, 1fr); }
  .article-grid--3 { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: var(--space-8); }

  .article-layout { grid-template-columns: 1fr; }
  .article-sidebar { position: static; }

  .home-cta { grid-template-columns: 1fr; }
  .cta-visual-grid { display: none; }

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

  .category-section-header { flex-wrap: wrap; }
  .category-section-link { order: 3; }

  .footer-bottom { flex-direction: column; gap: var(--space-2); text-align: center; }
}

/* ============================================================
   Responsive: 480px
   ============================================================ */
@media (max-width: 480px) {
  :root { --space-6: 1rem; }

  .categories-grid { grid-template-columns: 1fr; }
  .article-grid--3 { grid-template-columns: 1fr; }
  .article-grid--2 { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; }
  .hero-stats { flex-direction: column; gap: var(--space-4); }
  .article-hero-meta { flex-direction: column; align-items: flex-start; gap: var(--space-2); }
  .home-cta-buttons { flex-direction: column; }
}