/* ============================================
   MANUALE DI PROBABILITÀ — CSS Design System
   ============================================ */

/* ---------- Google Fonts ---------- */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&family=JetBrains+Mono:wght@400;500&display=swap');

/* ---------- CSS Custom Properties ---------- */
:root {
  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 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;

  /* Border radius */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-full: 9999px;

  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 400ms cubic-bezier(0.4, 0, 0.2, 1);

  /* Shadows (light) */
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.07), 0 2px 4px -2px rgba(0,0,0,0.05);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.08), 0 4px 6px -4px rgba(0,0,0,0.04);
  --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.1), 0 8px 10px -6px rgba(0,0,0,0.05);

  /* Layout */
  --max-width: 1200px;
  --content-width: 820px;
  --header-height: 64px;
  --chat-height: 64px;
}

/* ---------- Light Theme (default) ---------- */
[data-theme="light"] {
  --bg-primary: #f8f9fb;
  --bg-secondary: #ffffff;
  --bg-tertiary: #f1f3f8;
  --bg-code: #f4f4f8;

  --text-primary: #1a1a2e;
  --text-secondary: #4a4a68;
  --text-tertiary: #7c7c9a;
  --text-inverse: #ffffff;

  --accent: #6366f1;
  --accent-hover: #4f46e5;
  --accent-light: #eef2ff;
  --accent-subtle: rgba(99,102,241,0.08);

  --success: #10b981;
  --warning: #f59e0b;
  --danger: #ef4444;
  --info: #3b82f6;

  --border: #e2e5f1;
  --border-light: #f0f1f5;

  --card-bg: #ffffff;
  --card-hover-bg: #fafaff;

  --nav-bg: rgba(255,255,255,0.85);
  --nav-border: rgba(226,229,241,0.6);

  --glass-bg: rgba(255,255,255,0.7);
  --glass-border: rgba(255,255,255,0.4);

  --scrollbar-track: #f1f3f8;
  --scrollbar-thumb: #c4c8d8;

  --difficulty-base: #10b981;
  --difficulty-intermedio: #f59e0b;
  --difficulty-avanzato: #ef4444;

  color-scheme: light;
}

/* ---------- Dark Theme ---------- */
[data-theme="dark"] {
  --bg-primary: #0c0c1d;
  --bg-secondary: #141428;
  --bg-tertiary: #1a1a35;
  --bg-code: #1e1e3a;

  --text-primary: #e2e8f0;
  --text-secondary: #a0aec0;
  --text-tertiary: #718096;
  --text-inverse: #0c0c1d;

  --accent: #818cf8;
  --accent-hover: #6366f1;
  --accent-light: rgba(129,140,248,0.12);
  --accent-subtle: rgba(129,140,248,0.06);

  --success: #34d399;
  --warning: #fbbf24;
  --danger: #f87171;
  --info: #60a5fa;

  --border: #2d2d50;
  --border-light: #1f1f3a;

  --card-bg: #16162e;
  --card-hover-bg: #1c1c3a;

  --nav-bg: rgba(12,12,29,0.9);
  --nav-border: rgba(45,45,80,0.6);

  --glass-bg: rgba(20,20,40,0.7);
  --glass-border: rgba(45,45,80,0.4);

  --scrollbar-track: #141428;
  --scrollbar-thumb: #2d2d50;

  --difficulty-base: #34d399;
  --difficulty-intermedio: #fbbf24;
  --difficulty-avanzato: #f87171;

  color-scheme: dark;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

a:hover {
  color: var(--accent-hover);
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

::selection {
  background: var(--accent);
  color: var(--text-inverse);
}

/* Scrollbar */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}
::-webkit-scrollbar-track {
  background: var(--scrollbar-track);
}
::-webkit-scrollbar-thumb {
  background: var(--scrollbar-thumb);
  border-radius: var(--radius-full);
}
::-webkit-scrollbar-thumb:hover {
  background: var(--accent);
}

/* ---------- Header & Navigation ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: var(--nav-bg);
  backdrop-filter: blur(16px) saturate(180%);
  -webkit-backdrop-filter: blur(16px) saturate(180%);
  border-bottom: 1px solid var(--nav-border);
  height: var(--header-height);
  transition: background var(--transition-base), border-color var(--transition-base);
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-lg);
}

.header-logo-img {
  max-width: 200px;
  width: auto;
  display: block;
}

.site-logo {
  display: flex;
  align-items: center;
  text-decoration: none;
  flex-shrink: 0;
}


/* Navigation container */
.site-header nav {
  display: flex;
  align-items: center;
  height: 100%;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  list-style: none;
  margin: 0 !important;
  padding: 0 !important;
}

.nav-links li {
  display: flex;
  align-items: center;
  height: 100%;
  margin: 0 !important;
  padding: 0 !important;
}

.nav-links a {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-size: 0.95rem;
  font-weight: 500;
  transition: all var(--transition-fast);
  line-height: 1;
}

.nav-links a:hover {
  color: var(--accent);
  background: var(--bg-hover);
}

.nav-links a.active {
  color: var(--accent);
  background: var(--accent-subtle);
  font-weight: 600;
}

.nav-links a svg {
  width: 18px;
  height: 18px;
}

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

/* Search bar */
.search-bar {
  position: relative;
}

.search-bar input {
  width: 220px;
  padding: 8px 12px 8px 36px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border);
  border-radius: var(--radius-full);
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 0.85rem;
  outline: none;
  transition: all var(--transition-fast);
}

.search-bar input::placeholder {
  color: var(--text-tertiary);
}

.search-bar input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-subtle);
  width: 280px;
}

.search-bar .search-icon {
  position: absolute;
  left: 12px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-tertiary);
  width: 16px;
  height: 16px;
  pointer-events: none;
}

/* Mobile Search Icon Button (Magnifying glass) */
.search-mobile-btn {
  display: none;
  width: 40px;
  height: 40px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-secondary);
  color: var(--text-secondary);
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
}

.search-mobile-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-subtle);
}

.search-mobile-btn svg {
  width: 18px;
  height: 18px;
}

/* Theme toggle */
.theme-toggle {
  width: 40px;
  height: 40px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-secondary);
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
}

.theme-toggle:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-subtle);
}

.theme-toggle svg {
  width: 18px;
  height: 18px;
}

[data-theme="light"] .theme-toggle .icon-sun { display: none; }
[data-theme="light"] .theme-toggle .icon-moon { display: block; }
[data-theme="dark"] .theme-toggle .icon-sun { display: block; }
[data-theme="dark"] .theme-toggle .icon-moon { display: none; }

/* Mobile menu */
.mobile-menu-btn {
  display: none;
  width: 40px;
  height: 40px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-secondary);
  color: var(--text-secondary);
  cursor: pointer;
  align-items: center;
  justify-content: center;
}

.mobile-menu-btn svg {
  width: 20px;
  height: 20px;
}

/* ---------- Main Content ---------- */
.main-content {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-2xl) var(--space-lg);
  min-height: calc(100vh - var(--header-height) - 200px);
}

.content-narrow {
  max-width: var(--content-width);
  margin: 0 auto;
}

/* ---------- Hero Section ---------- */
.hero {
  text-align: center;
  padding: var(--space-3xl) 0;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  left: 50%;
  transform: translateX(-50%);
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, var(--accent-subtle) 0%, transparent 70%);
  pointer-events: none;
  z-index: -1;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 16px;
  background: var(--accent-light);
  color: var(--accent);
  border-radius: var(--radius-full);
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.03em;
  margin-bottom: var(--space-lg);
}

.hero-badge svg {
  width: 14px;
  height: 14px;
}

.hero h1 {
  font-size: clamp(2rem, 5vw, 3.2rem);
  font-weight: 800;
  line-height: 1.15;
  margin-bottom: var(--space-md);
  background: linear-gradient(135deg, var(--text-primary) 0%, var(--accent) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  font-size: 1.15rem;
  color: var(--text-secondary);
  max-width: 620px;
  margin: 0 auto var(--space-xl);
  line-height: 1.7;
}

.hero-actions {
  display: flex;
  gap: var(--space-md);
  justify-content: center;
  flex-wrap: wrap;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 24px;
  border-radius: var(--radius-sm);
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
}

.btn svg {
  width: 18px;
  height: 18px;
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent), #8b5cf6);
  color: white;
  box-shadow: 0 4px 14px rgba(99,102,241,0.35);
}

.btn-primary:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 20px rgba(99,102,241,0.45);
  color: white;
}

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

.btn-secondary:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-subtle);
}

/* ---------- Section Headings ---------- */
.section-heading {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-xl);
  flex-wrap: wrap;
  gap: var(--space-md);
}

.section-heading h2 {
  font-size: 1.6rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.section-heading h2 svg {
  width: 24px;
  height: 24px;
  color: var(--accent);
}

.section-heading .view-all {
  font-size: 0.9rem;
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: 4px;
}

.section-heading .view-all svg {
  width: 16px;
  height: 16px;
}

/* ---------- Cards Grid ---------- */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: var(--space-lg);
}

.cards-grid-3 {
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
}

/* ---------- Chapter Card ---------- */
.chapter-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  text-decoration: none;
  color: var(--text-primary);
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.chapter-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--accent), #a78bfa);
  opacity: 0;
  transition: opacity var(--transition-fast);
}

.chapter-card:hover {
  border-color: var(--accent);
  background: var(--card-hover-bg);
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  color: var(--text-primary);
}

.chapter-card:hover::before {
  opacity: 1;
}

.chapter-card-icon {
  width: 48px;
  height: 48px;
  background: var(--accent-light);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--space-md);
  color: var(--accent);
}

.chapter-card-icon svg {
  width: 24px;
  height: 24px;
}

.chapter-card h3 {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: var(--space-sm);
}

.chapter-card p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: var(--space-md);
}

.chapter-card-meta {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  font-size: 0.8rem;
  color: var(--text-tertiary);
}

.chapter-card-meta span {
  display: flex;
  align-items: center;
  gap: 4px;
}

.chapter-card-meta svg {
  width: 14px;
  height: 14px;
}

/* ---------- Lesson Card ---------- */
.lesson-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  text-decoration: none;
  color: var(--text-primary);
  display: flex;
  gap: var(--space-lg);
  transition: all var(--transition-base);
}

.lesson-card:hover {
  border-color: var(--accent);
  background: var(--card-hover-bg);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  color: var(--text-primary);
}

.lesson-card-number {
  flex-shrink: 0;
  width: 44px;
  height: 44px;
  background: var(--accent-light);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--accent);
}

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

.lesson-card-body h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 4px;
}

.lesson-card-body p {
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: var(--space-sm);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  line-clamp: 2;
  overflow: hidden;
}

.lesson-card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.tag {
  display: inline-flex;
  align-items: center;
  padding: 2px 10px;
  background: var(--bg-tertiary);
  border-radius: var(--radius-full);
  font-size: 0.75rem;
  color: var(--text-tertiary);
  font-weight: 500;
}

.tag-difficulty {
  font-weight: 600;
}

.tag-difficulty.base {
  background: rgba(16,185,129,0.1);
  color: var(--difficulty-base);
}

.tag-difficulty.intermedio {
  background: rgba(245,158,11,0.1);
  color: var(--difficulty-intermedio);
}

.tag-difficulty.avanzato {
  background: rgba(239,68,68,0.1);
  color: var(--difficulty-avanzato);
}

/* ---------- News Card ---------- */
.news-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  text-decoration: none;
  color: var(--text-primary);
  transition: all var(--transition-base);
}

.news-card:hover {
  border-color: var(--accent);
  background: var(--card-hover-bg);
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  color: var(--text-primary);
}

.news-card-date {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.8rem;
  color: var(--text-tertiary);
  margin-bottom: var(--space-sm);
}

.news-card-date svg {
  width: 14px;
  height: 14px;
}

.news-card h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
}

.news-card p {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.news-category {
  display: inline-flex;
  align-items: center;
  padding: 4px 12px;
  background: var(--accent-light);
  color: var(--accent);
  border-radius: var(--radius-full);
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-sm);
  line-height: 1;
}

/* ---------- Breadcrumbs ---------- */
.breadcrumbs {
  margin-bottom: var(--space-xl);
}

.breadcrumbs ol {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 4px;
  font-size: 0.85rem;
}

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

.breadcrumbs a {
  color: var(--text-tertiary);
  padding: 4px 6px;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

.breadcrumbs a:hover {
  color: var(--accent);
  background: var(--accent-subtle);
}

.breadcrumb-separator {
  color: var(--text-tertiary);
  display: flex;
  align-items: center;
}

.breadcrumb-separator svg {
  width: 14px;
  height: 14px;
}

.breadcrumbs li:last-child span {
  color: var(--text-primary);
  font-weight: 500;
}

/* ---------- Lesson Page ---------- */
.lesson-header {
  margin-bottom: var(--space-2xl);
  padding-bottom: var(--space-xl);
  border-bottom: 1px solid var(--border);
}

.lesson-header h1 {
  font-size: clamp(1.6rem, 3.5vw, 2.2rem);
  font-weight: 800;
  margin-bottom: var(--space-md);
  line-height: 1.25;
}

.lesson-meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-md);
  color: var(--text-tertiary);
  font-size: 0.85rem;
}

.lesson-meta-item {
  display: flex;
  align-items: center;
  gap: 6px;
}

.lesson-meta-item svg {
  width: 15px;
  height: 15px;
}

/* Lesson content — Markdown rendered */
.lesson-content {
  font-size: 1.02rem;
  line-height: 1.8;
}

.lesson-content h2 {
  font-size: 1.55rem;
  font-weight: 700;
  margin: var(--space-2xl) 0 var(--space-md);
  padding-bottom: var(--space-sm);
  border-bottom: 2px solid var(--border);
}

.lesson-content h3 {
  font-size: 1.25rem;
  font-weight: 600;
  margin: var(--space-xl) 0 var(--space-md);
  color: var(--accent);
}

.lesson-content h4 {
  font-size: 1.05rem;
  font-weight: 600;
  margin: var(--space-lg) 0 var(--space-sm);
}

.lesson-content p {
  margin-bottom: var(--space-md);
}

.lesson-content ul,
.lesson-content ol {
  margin-bottom: var(--space-md);
  padding-left: var(--space-xl);
}

.lesson-content li {
  margin-bottom: var(--space-xs);
}

.lesson-content strong {
  font-weight: 600;
  color: var(--text-primary);
}

.lesson-content blockquote {
  border-left: 4px solid var(--accent);
  padding: var(--space-md) var(--space-lg);
  margin: var(--space-lg) 0;
  background: var(--accent-subtle);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  color: var(--text-secondary);
  font-style: italic;
}

.lesson-content hr {
  border: none;
  height: 1px;
  background: var(--border);
  margin: var(--space-xl) 0;
}

.lesson-content code {
  font-family: var(--font-mono);
  background: var(--bg-code);
  padding: 2px 7px;
  border-radius: var(--radius-sm);
  font-size: 0.88em;
  border: 1px solid var(--border-light);
}

.lesson-content pre {
  background: var(--bg-code);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
  overflow-x: auto;
  margin: var(--space-lg) 0;
}

.lesson-content pre code {
  background: none;
  padding: 0;
  border: none;
  font-size: 0.85rem;
}

.lesson-content table {
  width: 100%;
  border-collapse: collapse;
  margin: var(--space-lg) 0;
  font-size: 0.92rem;
}

.lesson-content th,
.lesson-content td {
  padding: 10px 14px;
  text-align: left;
  border: 1px solid var(--border);
}

.lesson-content th {
  background: var(--bg-tertiary);
  font-weight: 600;
}

.lesson-content td {
  background: var(--card-bg);
}

/* KaTeX display */
.katex-display {
  margin: var(--space-lg) 0;
  padding: var(--space-md) 0;
  overflow-x: auto;
  overflow-y: hidden;
}

.katex {
  font-size: 1.1em;
}

/* JSXGraph */
.jsxgraph-container {
  margin: var(--space-xl) 0;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  overflow: hidden;
  background: var(--card-bg);
}

#jsxgraph-box,
.jsxgraph-box {
  width: 100%;
  height: 400px;
}

.jsxgraph-label {
  font-family: var(--font-sans) !important;
}

/* Lesson navigation */
.lesson-nav {
  display: flex;
  justify-content: space-between;
  gap: var(--space-md);
  margin-top: var(--space-2xl);
  padding-top: var(--space-xl);
  border-top: 1px solid var(--border);
}

.lesson-nav-btn {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-md) var(--space-lg);
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  text-decoration: none;
  transition: all var(--transition-fast);
  max-width: 48%;
}

.lesson-nav-btn:hover {
  border-color: var(--accent);
  background: var(--accent-subtle);
  color: var(--text-primary);
}

.lesson-nav-btn svg {
  flex-shrink: 0;
  width: 20px;
  height: 20px;
  color: var(--accent);
}

.lesson-nav-btn .nav-label {
  font-size: 0.78rem;
  color: var(--text-tertiary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  font-weight: 600;
}

.lesson-nav-btn .nav-title {
  font-size: 0.92rem;
  font-weight: 500;
}

.lesson-nav-btn.next {
  text-align: right;
  margin-left: auto;
}

/* ---------- AI Chat ---------- */
.ai-chat-bar {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 900;
  background: var(--glass-bg);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border-top: 1px solid var(--glass-border);
  padding: 10px var(--space-lg) 6px;
  transition: transform var(--transition-base);
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.ai-chat-inner {
  max-width: var(--content-width);
  width: 100%;
  margin: 0 auto;
  display: flex;
  gap: var(--space-sm);
  align-items: center;
}

.ai-chat-disclaimer {
  max-width: var(--content-width);
  width: 100%;
  margin: 0 auto;
  text-align: center;
  font-size: 0.7rem;
  color: var(--text-tertiary);
  opacity: 0.7;
}

.ai-chat-input-wrap {
  flex: 1;
  position: relative;
}

.ai-chat-input {
  width: 100%;
  padding: 12px 16px 12px 44px;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-full);
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 0.9rem;
  outline: none;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.ai-chat-input::placeholder {
  color: var(--text-tertiary);
}

.ai-chat-input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-subtle);
}

.ai-chat-icon {
  position: absolute;
  left: 14px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--accent);
  width: 20px;
  height: 20px;
  pointer-events: none;
}

.ai-chat-send {
  width: 44px;
  height: 44px;
  background: linear-gradient(135deg, var(--accent), #8b5cf6);
  border: none;
  border-radius: var(--radius-full);
  color: white;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
  flex-shrink: 0;
}

.ai-chat-send:hover {
  transform: scale(1.05);
  box-shadow: 0 4px 14px rgba(99,102,241,0.4);
}

.ai-chat-send svg {
  width: 18px;
  height: 18px;
}

/* AI responses area */
.ai-responses {
  margin-top: var(--space-2xl);
  padding-top: var(--space-xl);
  border-top: 2px solid var(--accent-light);
}

.ai-responses-title {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: var(--space-lg);
  color: var(--accent);
}

.ai-responses-title svg {
  width: 22px;
  height: 22px;
}

.ai-chat-clear-btn {
  margin-left: auto;
  background: none;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-muted);
  cursor: pointer;
  padding: 4px 8px;
  display: flex;
  align-items: center;
  gap: 4px;
  font-size: 0.8rem;
  transition: var(--transition);
}

.ai-chat-clear-btn:hover {
  color: #e74c3c;
  border-color: #e74c3c;
  background: rgba(231, 76, 60, 0.06);
}

.ai-chat-clear-btn svg {
  width: 14px;
  height: 14px;
}

.ai-message {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  margin-bottom: var(--space-md);
  animation: fadeInUp 0.4s ease;
  scroll-margin-top: 90px; /* Offset for sticky header */
}

.ai-message.role-user .ai-message-text {
  font-style: italic;
  color: var(--text-secondary);
}

.ai-message-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-sm);
  margin-bottom: var(--space-md);
  font-size: 0.82rem;
  color: var(--text-tertiary);
}

.ai-message-header-left {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.ai-message-time {
  font-size: 0.75rem;
  opacity: 0.7;
}

.ai-message-content {
  font-size: 0.98rem;
  line-height: 1.75;
  color: var(--text-primary);
}

.ai-message-text p {
  margin-bottom: var(--space-md);
}

.ai-message-text ul, 
.ai-message-text ol {
  padding-left: 2rem; /* Enough room for bullets */
  margin: var(--space-md) 0;
  display: block;
}

.ai-message-text ul {
  list-style-type: disc;
}

.ai-message-text ol {
  list-style-type: decimal;
}

.ai-message-text li {
  margin-bottom: var(--space-xs);
  padding-left: 0.5rem;
}

.ai-message-text hr {
  border: none;
  border-bottom: 2px dotted var(--border);
  margin: var(--space-xl) 0;
  opacity: 0.4;
  height: 0;
}

.ai-message-text strong {
  color: var(--accent);
  font-weight: 700;
}

/* Low message alert */
.ai-limit-alert {
  background: var(--accent-subtle);
  border: 1px solid var(--accent-light);
  border-radius: var(--radius-md);
  padding: var(--space-sm) var(--space-md);
  margin-top: var(--space-md);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  color: var(--accent);
  font-size: 0.85rem;
  font-weight: 600;
  animation: slideUp 0.4s ease;
}

.ai-limit-alert svg {
  width: 16px;
  height: 16px;
}

.ai-message-text {
  position: relative;
}

.ai-message-actions {
  display: flex;
  gap: var(--space-xs);
  margin-top: var(--space-md);
  padding-top: var(--space-sm);
  border-top: 1px solid var(--border-light);
  justify-content: flex-end;
}

.ai-action-btn {
  width: 32px;
  height: 32px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.ai-action-btn:hover {
  background: var(--accent-light);
  color: var(--accent);
  border-color: var(--accent);
  transform: translateY(-2px);
}

.ai-action-btn svg {
  width: 14px;
  height: 14px;
}

.ai-message-avatar {
  width: 28px;
  height: 28px;
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  font-weight: 700;
}

.ai-message-avatar.user {
  background: var(--accent-light);
  color: var(--accent);
}

.ai-message-avatar.ai {
  background: linear-gradient(135deg, var(--accent), #a78bfa);
  color: white;
}

.ai-message-content {
  font-size: 0.95rem;
  line-height: 1.7;
}

.ai-message-content p {
  margin-bottom: var(--space-sm);
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(12px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ---------- Pagination ---------- */
.pagination {
  margin-top: var(--space-2xl);
  display: flex;
  justify-content: center;
}

.pagination-list {
  display: flex;
  align-items: center;
  gap: 4px;
  list-style: none;
}

.pagination-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 4px;
  min-width: 40px;
  height: 40px;
  padding: 0 12px;
  border-radius: var(--radius-sm);
  background: var(--card-bg);
  border: 1px solid var(--border);
  color: var(--text-primary);
  font-size: 0.88rem;
  font-weight: 500;
  text-decoration: none;
  transition: all var(--transition-fast);
}

.pagination-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-subtle);
}

.pagination-btn.active {
  background: var(--accent);
  border-color: var(--accent);
  color: white;
  pointer-events: none;
}

.pagination-btn svg {
  width: 16px;
  height: 16px;
}

.pagination-ellipsis {
  padding: 0 8px;
  color: var(--text-tertiary);
}

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--border);
  padding: var(--space-2xl) var(--space-lg);
  margin-top: var(--space-3xl);
  text-align: center;
  color: var(--text-tertiary);
  font-size: 0.85rem;
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: var(--space-lg);
  margin-bottom: var(--space-md);
  flex-wrap: wrap;
}

.footer-links a {
  color: var(--text-secondary);
  font-weight: 500;
}

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

/* ---------- Search Page ---------- */
.search-page-input-wrap {
  position: relative;
  margin-bottom: var(--space-2xl);
}

.search-page-input {
  width: 100%;
  padding: 16px 20px 16px 52px;
  background: var(--card-bg);
  border: 2px solid var(--border);
  border-radius: var(--radius-lg);
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 1.1rem;
  outline: none;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.search-page-input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 4px var(--accent-subtle);
}

.search-page-input-wrap .search-icon {
  position: absolute;
  left: 18px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-tertiary);
  width: 22px;
  height: 22px;
}

.search-results-count {
  font-size: 0.9rem;
  color: var(--text-tertiary);
  margin-bottom: var(--space-lg);
}

.search-results {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.search-no-results {
  text-align: center;
  padding: var(--space-3xl) 0;
  color: var(--text-tertiary);
}

.search-no-results svg {
  width: 48px;
  height: 48px;
  margin: 0 auto var(--space-md);
  opacity: 0.4;
}

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

.fade-in-up.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ---------- Loading Skeleton ---------- */
.skeleton {
  background: linear-gradient(90deg, var(--bg-tertiary) 25%, var(--border-light) 50%, var(--bg-tertiary) 75%);
  background-size: 200% 100%;
  animation: shimmer 1.5s infinite;
  border-radius: var(--radius-sm);
}

@keyframes shimmer {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

/* ---------- Page with chat bar (add bottom padding) ---------- */
.page-lesson .main-content {
  padding-bottom: calc(var(--space-3xl) + var(--chat-height));
}

/* ---------- 404 ---------- */
.page-404 {
  text-align: center;
  padding: var(--space-3xl) 0;
}

/* ---------- News archive ---------- */
.news-archive-header {
  margin-bottom: var(--space-2xl);
}

.news-archive-header h1 {
  font-size: 1.8rem;
  font-weight: 800;
  margin-bottom: var(--space-sm);
}

.news-archive-header p {
  color: var(--text-secondary);
  font-size: 1.05rem;
}

/* ---------- News Detail ---------- */
.news-detail-header {
  margin-bottom: var(--space-2xl);
}

.news-detail-header h1 {
  font-size: clamp(1.5rem, 3.5vw, 2rem);
  font-weight: 800;
  margin-bottom: var(--space-md);
}

.news-detail-meta {
  display: flex;
  gap: var(--space-md);
  color: var(--text-tertiary);
  font-size: 0.85rem;
  flex-wrap: wrap;
}

.news-detail-meta span {
  display: flex;
  align-items: center;
  gap: 6px;
}

.news-detail-meta svg {
  width: 15px;
  height: 15px;
}

/* ---------- Responsive ---------- */
@media (max-width: 768px) {
  .header-inner {
    padding: 0 var(--space-md);
    gap: var(--space-md);
  }

  .header-logo-img {
    max-width: 170px;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: var(--header-height);
    left: 0;
    right: 0;
    background: var(--nav-bg);
    backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--nav-border);
    flex-direction: column;
    padding: var(--space-md);
  }

  .nav-links.open {
    display: flex;
  }

  .mobile-menu-btn {
    display: flex;
  }

  .search-bar {
    display: none;
  }

  .search-mobile-btn {
    display: flex;
  }

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

  .hero {
    padding: var(--space-xl) 0;
  }

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

  .cards-grid-3 {
    grid-template-columns: 1fr;
  }

  .lesson-nav {
    flex-direction: column;
  }

  .lesson-nav-btn {
    max-width: 100%;
  }

  .ai-chat-bar {
    padding: var(--space-sm) var(--space-md);
  }

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

@media (max-width: 480px) {
  .hero h1 {
    font-size: 1.7rem;
  }

  .hero-actions {
    flex-direction: column;
  }

  .hero-actions .btn {
    width: 100%;
    justify-content: center;
  }

  .lesson-header h1 {
    font-size: 1.4rem;
  }

  .header-logo-img {
    max-width: 140px;
  }

  .header-inner {
    gap: var(--space-xs);
  }
}
/* ---------- Modal (Limit Reached) ---------- */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.7);
  backdrop-filter: blur(8px);
  z-index: 2000;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
  padding: var(--space-lg);
}

.modal-overlay.active {
  opacity: 1;
  visibility: visible;
}

.modal-content {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  max-width: 450px;
  width: 100%;
  padding: var(--space-2xl);
  text-align: center;
  transform: scale(0.9) translateY(20px);
  transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
}

.modal-overlay.active .modal-content {
  transform: scale(1) translateY(0);
}

.modal-icon {
  width: 64px;
  height: 64px;
  background: var(--accent-light);
  color: var(--accent);
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto var(--space-xl);
}

.modal-icon svg {
  width: 32px;
  height: 32px;
}

.modal-title {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: var(--space-md);
  color: var(--accent);
}

.modal-text {
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: var(--space-xl);
}

/* ---------- Cookie Consent ---------- */
.cookie-consent {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 9999;
  background: var(--nav-bg);
  backdrop-filter: blur(12px);
  border-top: 1px solid var(--border);
  padding: var(--space-md) var(--space-lg);
  transform: translateY(100%);
  transition: transform 0.5s cubic-bezier(0.16, 1, 0.3, 1);
}

.cookie-consent.visible {
  transform: translateY(0);
}

.cookie-content {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-lg);
}

.cookie-content p {
  font-size: 0.9rem;
  color: var(--text-primary);
  margin: 0;
}

@media (max-width: 768px) {
  .cookie-content {
    flex-direction: column;
    text-align: center;
    gap: var(--space-md);
  }
}

/* ---------- Privacy Page ---------- */
.page-privacy .article-body {
  max-width: 800px;
  margin: 0 auto;
}

.page-privacy section h2 {
  font-size: 1.4rem;
  margin-bottom: var(--space-sm);
  color: var(--accent);
}

.page-privacy ul {
  padding-left: var(--space-lg);
  margin-bottom: var(--space-md);
}

.page-privacy li {
  margin-bottom: var(--space-xs);
  color: var(--text-secondary);
}

.header-banner {
  padding: var(--space-xl) 0;
  background: linear-gradient(to bottom, var(--bg-secondary), var(--bg-primary));
  text-align: center;
  margin-bottom: var(--space-lg);
}

.header-banner h1 {
  font-size: 2.5rem;
  font-weight: 800;
  margin-bottom: var(--space-sm);
}

.header-banner .subtitle {
  color: var(--text-secondary);
  font-size: 1.1rem;
}

.modal-btn {
  width: 100%;
  margin-top: var(--space-md);
  padding: 14px;
  background: var(--accent);
  color: white;
  border: none;
  border-radius: var(--radius-md);
  font-weight: 700;
  font-size: 0.95rem;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.modal-btn:hover {
  background: var(--accent-hover);
  transform: translateY(-2px);
}

/* ---------- Social Share ---------- */
.social-share {
  margin-top: var(--space-2xl);
  padding-top: var(--space-xl);
  border-top: 1px solid var(--border);
  display: flex;
  align-items: center;
  gap: var(--space-lg);
  flex-wrap: wrap;
}

.social-share .share-label {
  font-weight: 600;
  color: var(--text-primary);
  font-size: 1rem;
}

.social-share .share-buttons {
  display: flex;
  gap: var(--space-sm);
}

.share-btn {
  width: 42px;
  height: 42px;
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  transition: all var(--transition-fast);
  text-decoration: none;
  background: var(--bg-tertiary);
  border: 1px solid var(--border);
}

.share-btn svg {
  width: 20px;
  height: 20px;
}

/* Hover effects with brand colors */
.share-facebook:hover { background: #1877f2; border-color: #1877f2; color: white; transform: translateY(-3px); box-shadow: 0 4px 12px rgba(24,119,242,0.3); }
.share-x:hover { background: #000000; border-color: #000000; color: white; transform: translateY(-3px); box-shadow: 0 4px 12px rgba(0,0,0,0.3); }
.share-linkedin:hover { background: #0a66c2; border-color: #0a66c2; color: white; transform: translateY(-3px); box-shadow: 0 4px 12px rgba(10,102,194,0.3); }
.share-whatsapp:hover { background: #25d366; border-color: #25d366; color: white; transform: translateY(-3px); box-shadow: 0 4px 12px rgba(37,211,102,0.3); }

/* Base icon colors */
.share-facebook { color: #1877f2; }
.share-x { color: var(--text-primary); } /* Black in light, White in dark */
.share-linkedin { color: #0a66c2; }
.share-whatsapp { color: #25d366; }

[data-theme="dark"] .share-x:hover {
  background: #ffffff;
  border-color: #ffffff;
  color: #000000;
  box-shadow: 0 4px 12px rgba(255,255,255,0.3);
}