/* ============================================
   LEARNING WITH DATA - DESIGN SYSTEM v4.0
   Fully Responsive: Mobile · iPad · Desktop
   Material 3 + Glassmorphism + SaaS Premium
   ============================================ */

/* ============================================
   1. CSS CUSTOM PROPERTIES / DESIGN TOKENS
   ============================================ */
:root {
  /* Brand Colors */
  --brand-primary: #4F46E5;
  --brand-primary-hover: #4338CA;
  --brand-primary-light: #EEF2FF;
  --brand-secondary: #10B981;
  --brand-secondary-hover: #059669;
  --brand-accent: #F59E0B;
  --brand-accent-pink: #EC4899;

  /* Gradient Tokens */
  --gradient-hero: linear-gradient(135deg, #0f0c29 0%, #302b63 50%, #24243e 100%);
  --gradient-brand: linear-gradient(135deg, #4F46E5 0%, #7C3AED 100%);
  --gradient-emerald: linear-gradient(135deg, #10B981 0%, #059669 100%);
  --gradient-card: linear-gradient(135deg, rgba(255,255,255,0.1) 0%, rgba(255,255,255,0.05) 100%);

  /* Neutral Colors - Light Mode */
  --bg-primary: #FAFAFA;
  --bg-secondary: #F3F4F6;
  --bg-card: #FFFFFF;
  --text-primary: #111827;
  --text-secondary: #4B5563;
  --text-muted: #9CA3AF;
  --border-color: #E5E7EB;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.08);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.08);
  --shadow-lg: 0 20px 40px rgba(0,0,0,0.1);
  --shadow-xl: 0 25px 50px rgba(0,0,0,0.12);
  --shadow-brand: 0 10px 30px rgba(79,70,229,0.25);

  /* Glassmorphism */
  --glass-bg: rgba(255, 255, 255, 0.85);
  --glass-bg-dark: rgba(17, 24, 39, 0.75);
  --glass-border: rgba(255, 255, 255, 0.3);
  --glass-border-dark: rgba(255, 255, 255, 0.08);
  --backdrop-blur: blur(20px);

  /* Typography */
  --font-heading: 'Outfit', 'Inter', sans-serif;
  --font-body: 'Inter', 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

  /* Spacing System */
  --space-xs: 4px;  --space-sm: 8px;   --space-md: 16px;
  --space-lg: 24px; --space-xl: 32px;  --space-2xl: 48px;
  --space-3xl: 64px; --space-4xl: 96px; --space-5xl: 128px;

  /* Border Radius */
  --radius-sm: 8px;  --radius-md: 12px; --radius-lg: 16px;
  --radius-xl: 24px; --radius-full: 9999px;

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-base: 0.3s ease;
  --transition-slow: 0.5s ease;
}

/* Dark Mode Overrides */
html.dark {
  --bg-primary: #0B0F1A;
  --bg-secondary: #111827;
  --bg-card: #1F2937;
  --text-primary: #F9FAFB;
  --text-secondary: #D1D5DB;
  --text-muted: #6B7280;
  --border-color: #374151;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.3);
  --shadow-lg: 0 20px 40px rgba(0,0,0,0.4);
  --glass-bg: rgba(17, 24, 39, 0.9);
  --glass-border: rgba(255, 255, 255, 0.08);
}

/* ============================================
   2. RESET & BASE
   ============================================ */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

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

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

img { max-width: 100%; height: auto; display: block; }
a { color: var(--brand-primary); text-decoration: none; transition: color var(--transition-fast); }
a:hover { color: var(--brand-primary-hover); }
ul, ol { list-style: none; }
button { cursor: pointer; border: none; background: none; font-family: inherit; }

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 800;
  line-height: 1.2;
  color: var(--text-primary);
}
h1 { font-size: clamp(2rem, 5vw, 4rem); }
h2 { font-size: clamp(1.6rem, 3.5vw, 2.8rem); }
h3 { font-size: clamp(1.15rem, 2vw, 1.6rem); }
h4 { font-size: 1.15rem; }
p { color: var(--text-secondary); line-height: 1.8; }

/* ============================================
   3. LAYOUT UTILITIES
   ============================================ */
.container {
  max-width: 1240px;
  margin: 0 auto;
  padding: 0 var(--space-xl);
}
.container-sm {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 var(--space-xl);
}
.text-center { text-align: center; }
.text-gradient {
  background: var(--gradient-brand);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.sr-only {
  position: absolute; width: 1px; height: 1px;
  padding: 0; margin: -1px; overflow: hidden;
  clip: rect(0,0,0,0); border: 0;
}

/* ─── RESPONSIVE GRID SYSTEM ─────────────────
   Breakpoints:
   - Desktop  : > 1024px  → full columns
   - iPad     : 769–1024px → 2 columns max
   - Mobile   : ≤ 768px   → 1 column
   ─────────────────────────────────────────── */
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-xl);
}
.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-xl);
}
.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-xl);
}
.grid-auto {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-xl);
}

/* ─── RESPONSIVE SPLIT LAYOUTS ───────────────
   Use these for 2-column text+image sections
   ─────────────────────────────────────────── */
.split-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-4xl);
  align-items: center;
}
.split-layout-wide {
  display: grid;
  grid-template-columns: 1fr 1.2fr;
  gap: var(--space-4xl);
  align-items: center;
}
.split-layout-sidebar {
  display: grid;
  grid-template-columns: 1fr 380px;
  gap: var(--space-3xl);
  align-items: start;
}

/* ─── SECTION BADGES ─────────────────────── */
.section-badge {
  display: inline-flex; align-items: center; gap: var(--space-sm);
  background: var(--brand-primary-light); color: var(--brand-primary);
  padding: 6px 16px; border-radius: var(--radius-full);
  font-size: 0.85rem; font-weight: 600; margin-bottom: var(--space-lg);
}
html.dark .section-badge { background: rgba(79,70,229,0.15); }

/* ============================================
   4. BUTTONS
   ============================================ */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  gap: var(--space-sm); padding: 12px 28px;
  border-radius: var(--radius-md); font-weight: 600; font-size: 1rem;
  transition: all var(--transition-base); cursor: pointer; border: none;
  font-family: var(--font-body); white-space: nowrap;
}
.btn-primary {
  background: var(--gradient-brand); color: #fff;
  box-shadow: var(--shadow-brand);
}
.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 15px 35px rgba(79,70,229,0.4);
  color: #fff;
}
.btn-secondary {
  background: transparent; color: var(--brand-primary);
  border: 2px solid var(--brand-primary);
}
.btn-secondary:hover {
  background: var(--brand-primary); color: #fff;
  transform: translateY(-2px);
}
.btn-ghost {
  background: var(--glass-bg); backdrop-filter: var(--backdrop-blur);
  color: var(--text-primary); border: 1px solid var(--glass-border);
}
.btn-ghost:hover { background: var(--bg-card); transform: translateY(-1px); }
.btn-lg { padding: 16px 36px; font-size: 1.05rem; border-radius: var(--radius-lg); }
.btn-sm { padding: 8px 18px; font-size: 0.875rem; }
.btn-emerald {
  background: var(--gradient-emerald); color: #fff;
  box-shadow: 0 10px 30px rgba(16,185,129,0.25);
}
.btn-emerald:hover {
  transform: translateY(-2px);
  box-shadow: 0 15px 35px rgba(16,185,129,0.4); color: #fff;
}

/* ============================================
   5. HEADER & NAVIGATION
   ============================================ */
.site-header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  background: var(--bg-primary);
  border-bottom: 1px solid var(--border-color);
  transition: all var(--transition-base);
}
.site-header.scrolled {
  background: var(--glass-bg);
  backdrop-filter: var(--backdrop-blur);
  -webkit-backdrop-filter: var(--backdrop-blur);
  border-bottom: 1px solid var(--glass-border);
  box-shadow: var(--shadow-md);
}
.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  height: 72px;
}
.site-logo {
  display: flex; align-items: center; gap: var(--space-sm);
  font-family: var(--font-heading); font-weight: 800; font-size: 1.35rem;
  color: var(--text-primary); flex-shrink: 0;
}
.logo-mark {
  width: 36px; height: 36px; flex-shrink: 0;
  background: var(--gradient-brand);
  border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.1rem;
}
.logo-text span { color: var(--brand-primary); }

.main-nav { display: flex; align-items: center; gap: var(--space-xs); }
.main-nav a {
  padding: 8px 12px; border-radius: var(--radius-sm);
  font-weight: 500; font-size: 0.95rem; color: var(--text-primary);
  transition: all var(--transition-fast);
}
.main-nav a:hover { background: var(--bg-secondary); color: var(--brand-primary); }

.header-actions { display: flex; align-items: center; gap: var(--space-md); }
.theme-toggle {
  width: 40px; height: 40px; flex-shrink: 0;
  border-radius: var(--radius-sm);
  display: flex; align-items: center; justify-content: center;
  background: var(--bg-secondary); color: var(--text-primary);
  transition: all var(--transition-base); font-size: 1.1rem;
}
.theme-toggle:hover { background: var(--border-color); }

/* Mobile Hamburger */
.mobile-menu-btn {
  display: none; flex-direction: column; gap: 5px;
  width: 40px; height: 40px; justify-content: center;
  align-items: center; border-radius: var(--radius-sm);
  background: var(--bg-secondary); flex-shrink: 0;
}
.mobile-menu-btn span {
  width: 22px; height: 2px;
  background: var(--text-primary); border-radius: 2px;
  transition: all var(--transition-base);
}
.mobile-nav {
  display: none; flex-direction: column; gap: var(--space-sm);
  padding: var(--space-md) var(--space-lg); background: var(--glass-bg);
  backdrop-filter: var(--backdrop-blur);
  border-bottom: 1px solid var(--glass-border);
  max-height: calc(100vh - 72px);
  overflow-y: auto;
}
.mobile-nav a {
  padding: 12px var(--space-md); border-radius: var(--radius-sm);
  font-weight: 500; color: var(--text-primary); display: block;
}
.mobile-nav a:hover { background: var(--brand-primary-light); color: var(--brand-primary); }
.mobile-nav .btn { display: flex; text-align: center; justify-content: center; }

/* ============================================
   6. HERO SECTION
   ============================================ */
.hero {
  position: relative; min-height: 100vh;
  display: flex; align-items: center;
  overflow: hidden; padding-top: 72px;
  background: linear-gradient(to right, rgba(15, 12, 41, 0.95), rgba(48, 43, 99, 0.8)), url('../images/hero/hero_banner.png') center/cover no-repeat;
}
.hero-bg-image {
  position: absolute; inset: 0;
  background-size: cover; background-position: center;
  opacity: 0.35;
}
.hero-overlay {
  position: absolute; inset: 0;
  background: linear-gradient(to right, rgba(15,12,41,0.9) 0%, rgba(15,12,41,0.5) 60%, transparent 100%);
}
.hero-inner {
  position: relative; z-index: 2;
  display: grid; grid-template-columns: 1fr 1fr;
  align-items: center; gap: var(--space-4xl);
  padding: var(--space-4xl) 0;
}
.hero-content { max-width: 600px; }
.hero-eyebrow {
  display: inline-flex; align-items: center; gap: var(--space-sm);
  background: rgba(79,70,229,0.2); border: 1px solid rgba(79,70,229,0.4);
  color: #A5B4FC; padding: 6px 18px;
  border-radius: var(--radius-full); font-size: 0.875rem;
  font-weight: 600; margin-bottom: var(--space-xl);
  backdrop-filter: var(--backdrop-blur);
}
.hero-title { color: #fff; margin-bottom: var(--space-lg); }
.hero-title .accent { color: #A5B4FC; }
.hero-subtitle {
  font-size: 1.15rem; color: rgba(255,255,255,0.75);
  margin-bottom: var(--space-2xl); max-width: 520px; line-height: 1.8;
}
.hero-cta { display: flex; gap: var(--space-md); flex-wrap: wrap; margin-bottom: var(--space-3xl); }
.hero-stats {
  display: flex; gap: var(--space-2xl);
  padding-top: var(--space-2xl);
  border-top: 1px solid rgba(255,255,255,0.1);
  flex-wrap: wrap;
}
.hero-stat-num {
  font-family: var(--font-heading); font-size: 1.9rem;
  font-weight: 800; color: #fff; display: block;
}
.hero-stat-label { font-size: 0.85rem; color: rgba(255,255,255,0.6); }
.hero-visual {
  position: relative; display: flex; justify-content: center; align-items: center;
}
.hero-image-wrap {
  width: 100%; max-width: 520px;
  border-radius: var(--radius-xl); overflow: hidden;
  box-shadow: 0 30px 80px rgba(0,0,0,0.5);
  border: 1px solid rgba(255,255,255,0.1);
}
.hero-image-wrap img { width: 100%; height: 380px; object-fit: cover; }

/* Floating Cards */
.floating-card {
  position: absolute;
  background: var(--glass-bg-dark);
  backdrop-filter: var(--backdrop-blur);
  border: 1px solid rgba(255,255,255,0.12);
  border-radius: var(--radius-lg); padding: 14px 18px;
  color: #fff; box-shadow: var(--shadow-lg);
}
.floating-card-1 { top: 10%; right: -20px; animation: float 6s ease-in-out infinite; }
.floating-card-2 { bottom: 15%; left: -20px; animation: float 5s ease-in-out infinite 1.5s; }
.floating-card .card-value { font-size: 1.5rem; font-weight: 800; color: #A5B4FC; }
.floating-card .card-label { font-size: 0.75rem; color: rgba(255,255,255,0.6); }
.floating-card .card-tag { font-size: 0.7rem; color: #34D399; font-weight: 600; }

@keyframes float {
  0%, 100% { transform: translateY(0px); }
  50% { transform: translateY(-12px); }
}

/* ============================================
   7. SECTION LAYOUTS
   ============================================ */
.section { padding: var(--space-5xl) 0; }
.section-sm { padding: var(--space-3xl) 0; }
.section-header { text-align: center; max-width: 680px; margin: 0 auto var(--space-4xl); }
.section-header h2 { margin-bottom: var(--space-md); }
.section-header p { font-size: 1.05rem; }
.section-alt { background: var(--bg-secondary); }

/* ============================================
   8. CARDS
   ============================================ */
.glass-card {
  background: var(--glass-bg);
  backdrop-filter: var(--backdrop-blur);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-md);
  transition: all var(--transition-base);
}
.glass-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-xl); }

.card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-sm); overflow: hidden;
  transition: all var(--transition-base);
}
.card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }

/* Course Cards */
.course-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  overflow: hidden; transition: all var(--transition-base);
  display: flex; flex-direction: column;
}
.course-card:hover { transform: translateY(-6px); box-shadow: var(--shadow-xl); }
.course-card-img {
  height: 200px; overflow: hidden; position: relative;
  background: var(--gradient-brand);
}
.course-card-img img { width: 100%; height: 100%; object-fit: cover; }
.course-card-badge {
  position: absolute; top: 12px; left: 12px;
  background: var(--brand-secondary); color: #fff;
  padding: 4px 12px; border-radius: var(--radius-full);
  font-size: 0.75rem; font-weight: 700; text-transform: uppercase;
}
.course-card-body { padding: var(--space-xl); flex: 1; display: flex; flex-direction: column; }
.course-card-meta {
  display: flex; gap: var(--space-sm); flex-wrap: wrap;
  margin-bottom: var(--space-md); font-size: 0.8rem;
  color: var(--text-muted);
}
.course-card-title { font-size: 1.15rem; font-weight: 700; margin-bottom: var(--space-sm); color: var(--text-primary); }
.course-card-desc { font-size: 0.9rem; color: var(--text-secondary); margin-bottom: var(--space-lg); flex: 1; }
.course-card-footer {
  display: flex; align-items: center; justify-content: space-between;
  padding-top: var(--space-md); border-top: 1px solid var(--border-color);
  gap: var(--space-sm); flex-wrap: wrap;
}
.course-card-price { font-size: 1.4rem; font-weight: 800; color: var(--brand-primary); }
.course-card-price .original {
  font-size: 0.9rem; color: var(--text-muted);
  text-decoration: line-through; margin-right: 4px;
}

/* Blog Cards */
.blog-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl); overflow: hidden;
  transition: all var(--transition-base);
  display: flex; flex-direction: column;
}
.blog-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.blog-card-img { height: 200px; overflow: hidden; flex-shrink: 0; }
.blog-card-img img { width: 100%; height: 100%; object-fit: cover; transition: transform var(--transition-slow); }
.blog-card:hover .blog-card-img img { transform: scale(1.05); }
.blog-card-body { padding: var(--space-xl); flex: 1; display: flex; flex-direction: column; }
.blog-card-cat {
  display: inline-block; color: var(--brand-primary); font-size: 0.8rem;
  font-weight: 600; text-transform: uppercase; letter-spacing: 0.5px;
  margin-bottom: var(--space-sm);
}
.blog-card-title { font-size: 1.05rem; font-weight: 700; margin-bottom: var(--space-sm); color: var(--text-primary); line-height: 1.4; }
.blog-card-meta { display: flex; gap: var(--space-md); font-size: 0.8rem; color: var(--text-muted); margin-bottom: var(--space-md); flex-wrap: wrap; }
.blog-card-excerpt { font-size: 0.875rem; color: var(--text-secondary); line-height: 1.7; flex: 1; }

/* Feature Cards */
.feature-card { padding: var(--space-2xl); }
.feature-icon {
  width: 56px; height: 56px;
  background: var(--brand-primary-light);
  border-radius: var(--radius-lg);
  display: flex; align-items: center; justify-content: center;
  font-size: 1.6rem; margin-bottom: var(--space-lg);
}
html.dark .feature-icon { background: rgba(79,70,229,0.15); }
.feature-card h3 { margin-bottom: var(--space-sm); }

/* Stat Cards */
.stat-card {
  text-align: center; padding: var(--space-2xl);
  background: var(--bg-card); border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
}
.stat-num {
  font-family: var(--font-heading); font-size: 2.8rem; font-weight: 900;
  color: var(--brand-primary); line-height: 1;
  display: block; margin-bottom: var(--space-sm);
}
.stat-label { color: var(--text-muted); font-size: 0.875rem; font-weight: 500; }

/* Testimonial Cards */
.testimonial-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl); padding: var(--space-2xl);
  position: relative; display: flex; flex-direction: column;
}
.testimonial-card::before {
  content: '"'; font-size: 6rem; line-height: 0;
  color: var(--brand-primary); opacity: 0.15;
  position: absolute; top: 30px; left: 24px;
  font-family: Georgia, serif;
}
.testimonial-text {
  font-size: 0.95rem; color: var(--text-secondary);
  line-height: 1.8; margin-bottom: var(--space-xl);
  font-style: italic; flex: 1;
}
.testimonial-author { display: flex; align-items: center; gap: var(--space-md); flex-wrap: wrap; }
.testimonial-avatar {
  width: 46px; height: 46px; border-radius: 50%; flex-shrink: 0;
  background: var(--gradient-brand);
  display: flex; align-items: center; justify-content: center;
  color: #fff; font-weight: 700; font-size: 0.9rem;
}
.testimonial-name { font-weight: 700; color: var(--text-primary); }
.testimonial-role { font-size: 0.8rem; color: var(--text-muted); }
.testimonial-stars { color: var(--brand-accent); font-size: 0.9rem; margin-bottom: var(--space-md); }

/* ============================================
   9. AUTHOR BOX (EEAT)
   ============================================ */
.author-box {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl); padding: var(--space-2xl);
  display: flex; gap: var(--space-xl); align-items: flex-start;
  margin: var(--space-3xl) 0;
}
.author-avatar {
  width: 80px; height: 80px; border-radius: 50%; flex-shrink: 0;
  object-fit: cover;
  border: 3px solid var(--brand-primary);
}
.author-name { font-size: 1.05rem; font-weight: 700; margin-bottom: 4px; }
.author-title { font-size: 0.85rem; color: var(--brand-primary); font-weight: 600; margin-bottom: var(--space-sm); }
.author-bio { font-size: 0.875rem; color: var(--text-secondary); line-height: 1.7; }
.author-credentials {
  display: flex; gap: var(--space-sm); flex-wrap: wrap; margin-top: var(--space-sm);
}
.credential-badge {
  background: var(--brand-primary-light); color: var(--brand-primary);
  padding: 3px 10px; border-radius: var(--radius-full);
  font-size: 0.75rem; font-weight: 600;
}
html.dark .credential-badge { background: rgba(79,70,229,0.15); }

/* ============================================
   10. TRUST SIGNALS
   ============================================ */
.trust-bar {
  background: var(--bg-secondary);
  padding: var(--space-lg) 0;
  border-bottom: 1px solid var(--border-color);
}
.trust-bar-inner {
  display: flex; align-items: center; justify-content: center;
  gap: var(--space-2xl); flex-wrap: wrap;
}
.trust-item {
  display: flex; align-items: center; gap: var(--space-sm);
  font-size: 0.875rem; color: var(--text-secondary); font-weight: 500;
}
.trust-icon { font-size: 1.1rem; }

.social-proof { display: flex; align-items: center; gap: var(--space-md); flex-wrap: wrap; }
.proof-avatars { display: flex; }
.proof-avatars span {
  width: 34px; height: 34px; border-radius: 50%;
  background: var(--gradient-brand);
  border: 2px solid var(--bg-card);
  display: inline-flex; align-items: center; justify-content: center;
  font-size: 0.75rem; color: #fff; font-weight: 700;
  margin-left: -8px;
}
.proof-avatars span:first-child { margin-left: 0; }
.proof-text { font-size: 0.85rem; color: var(--text-secondary); }
.proof-text strong { color: var(--text-primary); }

/* ============================================
   11. BREADCRUMB
   ============================================ */
.breadcrumb {
  display: flex; align-items: center; gap: 6px;
  font-size: 0.85rem; flex-wrap: wrap;
  padding: var(--space-md) 0;
}
.breadcrumb a { color: var(--text-muted); }
.breadcrumb a:hover { color: var(--brand-primary); }
.breadcrumb-sep { color: var(--text-muted); }
.breadcrumb-current { color: var(--text-primary); font-weight: 500; }

/* ============================================
   12. FOOTER
   ============================================ */
.site-footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: var(--space-5xl) 0 var(--space-2xl);
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.8fr 1fr 1fr 1fr;
  gap: var(--space-3xl); margin-bottom: var(--space-4xl);
}
.footer-brand { max-width: 280px; }
.footer-brand p { font-size: 0.875rem; margin-top: var(--space-md); line-height: 1.7; }
.footer-social { display: flex; gap: var(--space-sm); margin-top: var(--space-lg); flex-wrap: wrap; }
.footer-social a {
  width: 38px; height: 38px;
  border-radius: var(--radius-sm);
  background: var(--bg-card); border: 1px solid var(--border-color);
  display: flex; align-items: center; justify-content: center;
  transition: all var(--transition-base); font-size: 1rem;
}
.footer-social a:hover {
  background: var(--brand-primary); border-color: var(--brand-primary);
  color: #fff; transform: translateY(-2px);
}
.footer-col-title {
  font-size: 0.8rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: 0.8px; color: var(--text-primary); margin-bottom: var(--space-lg);
}
.footer-col ul { display: flex; flex-direction: column; gap: var(--space-md); }
.footer-col ul a { color: var(--text-muted); font-size: 0.875rem; transition: color var(--transition-fast); }
.footer-col ul a:hover { color: var(--brand-primary); }
.footer-bottom {
  padding-top: var(--space-xl); border-top: 1px solid var(--border-color);
  display: flex; justify-content: space-between; align-items: center;
  flex-wrap: wrap; gap: var(--space-md);
}
.footer-bottom p { font-size: 0.8rem; color: var(--text-muted); }
.footer-bottom a { color: var(--text-muted); font-size: 0.8rem; }
.footer-bottom a:hover { color: var(--brand-primary); }
.footer-legal { display: flex; gap: var(--space-lg); }

/* ============================================
   13. MISC COMPONENTS
   ============================================ */
.tag {
  display: inline-block; background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  color: var(--text-secondary); padding: 4px 12px;
  border-radius: var(--radius-full); font-size: 0.8rem; font-weight: 500;
}
.tag:hover { background: var(--brand-primary-light); color: var(--brand-primary); border-color: transparent; }

.highlight-box {
  background: var(--brand-primary-light); border-left: 4px solid var(--brand-primary);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: var(--space-lg) var(--space-xl); margin: var(--space-xl) 0;
}
html.dark .highlight-box { background: rgba(79,70,229,0.1); }
.highlight-box p { color: var(--brand-primary); margin: 0; }

.separator { height: 1px; background: var(--border-color); margin: var(--space-2xl) 0; }

/* Progress / Rating Stars */
.stars { color: #F59E0B; letter-spacing: 2px; }
.rating { display: flex; align-items: center; gap: var(--space-sm); font-size: 0.875rem; flex-wrap: wrap; }
.rating-num { font-weight: 700; color: var(--text-primary); }
.rating-count { color: var(--text-muted); }

/* Code blocks */
pre {
  background: #1e2130; border-radius: var(--radius-lg);
  padding: var(--space-xl); overflow-x: auto;
  margin: var(--space-xl) 0;
  font-family: var(--font-mono); font-size: 0.85rem; line-height: 1.7;
}
code {
  background: var(--bg-secondary); color: var(--brand-primary);
  padding: 2px 6px; border-radius: 4px;
  font-family: var(--font-mono); font-size: 0.875em;
}

/* Newsletter Form */
.newsletter-form { display: flex; gap: var(--space-sm); flex-wrap: wrap; }
.newsletter-input {
  flex: 1; min-width: 220px; padding: 12px 18px;
  background: var(--bg-card); border: 1px solid var(--border-color);
  border-radius: var(--radius-md); font-family: var(--font-body); font-size: 1rem;
  color: var(--text-primary); outline: none; transition: border-color var(--transition-fast);
}
.newsletter-input:focus { border-color: var(--brand-primary); }
.newsletter-input::placeholder { color: var(--text-muted); }

/* ============================================
   14. ANIMATIONS
   ============================================ */
@keyframes float { 0%, 100% { transform: translateY(0px); } 50% { transform: translateY(-12px); } }
@keyframes fadeInUp { from { opacity: 0; transform: translateY(30px); } to { opacity: 1; transform: translateY(0); } }
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
@keyframes slideInRight { from { opacity: 0; transform: translateX(30px); } to { opacity: 1; transform: translateX(0); } }

.animate-fade-up { animation: fadeInUp 0.7s ease forwards; }
.animate-fade-in { animation: fadeIn 0.5s ease forwards; }
.delay-1 { animation-delay: 0.1s; opacity: 0; }
.delay-2 { animation-delay: 0.2s; opacity: 0; }
.delay-3 { animation-delay: 0.3s; opacity: 0; }
.delay-4 { animation-delay: 0.4s; opacity: 0; }

/* Scroll Reveal */
.reveal { opacity: 0; transform: translateY(30px); transition: all 0.7s ease; }
.reveal.is-visible { opacity: 1; transform: translateY(0); }

/* ============================================
   15. RESPONSIVE — TABLET / iPAD (≤ 1024px)
   ============================================ */
@media (max-width: 1024px) {

  /* Header */
  .main-nav a { padding: 7px 10px; font-size: 0.9rem; }

  /* Hero */
  .hero-inner { grid-template-columns: 1fr; text-align: center; gap: var(--space-2xl); }
  .hero-content { max-width: 100%; }
  .hero-subtitle { max-width: 100%; margin-left: auto; margin-right: auto; }
  .hero-cta { justify-content: center; }
  .hero-stats { justify-content: center; gap: var(--space-xl); }
  .hero-visual { display: none; }

  /* Grid: 3-col → 2-col on iPad */
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }

  /* Split layouts → stack on iPad */
  .split-layout,
  .split-layout-wide { grid-template-columns: 1fr; gap: var(--space-2xl); }

  /* Course detail sidebar → stack */
  .split-layout-sidebar {
    grid-template-columns: 1fr;
  }

  /* Footer: 4-col → 2-col */
  .footer-grid { grid-template-columns: 1fr 1fr; gap: var(--space-2xl); }
  .footer-brand { max-width: 100%; }

  /* Section spacing */
  .section { padding: var(--space-4xl) 0; }
  .section-header { margin-bottom: var(--space-3xl); }
}

/* ============================================
   16. RESPONSIVE — MOBILE (≤ 768px)
   ============================================ */
@media (max-width: 768px) {

  /* Container */
  .container, .container-sm { padding: 0 var(--space-lg); }

  /* Typography */
  h1 { font-size: clamp(1.75rem, 8vw, 2.5rem); }
  h2 { font-size: clamp(1.4rem, 6vw, 2rem); }
  h3 { font-size: clamp(1.1rem, 4vw, 1.4rem); }

  /* Header */
  .main-nav { display: none; }
  .header-actions .btn-sm { display: none; }
  .mobile-menu-btn { display: flex; }
  .mobile-nav.open { display: flex; }

  /* All grids → 1 column */
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }

  /* Split layouts → always stack */
  .split-layout,
  .split-layout-wide,
  .split-layout-sidebar { grid-template-columns: 1fr; gap: var(--space-xl); }

  /* Footer → 2-col then single */
  .footer-grid { grid-template-columns: 1fr 1fr; gap: var(--space-xl); }
  .footer-brand { grid-column: 1 / -1; max-width: 100%; }
  .footer-bottom { flex-direction: column; text-align: center; }

  /* Trust bar */
  .trust-bar-inner { gap: var(--space-md); }

  /* Author Box → stack */
  .author-box { flex-direction: column; align-items: center; text-align: center; }

  /* Hero Stats */
  .hero-stats { gap: var(--space-xl); justify-content: center; }

  /* Buttons */
  .hero-cta { flex-direction: column; align-items: stretch; }
  .hero-cta .btn { text-align: center; justify-content: center; }

  /* Sections */
  .section { padding: var(--space-3xl) 0; }
  .section-header { margin-bottom: var(--space-2xl); }

  /* Code blocks */
  pre { font-size: 0.8rem; padding: var(--space-md); }

  /* Newsletter */
  .newsletter-form { flex-direction: column; }
  .newsletter-input { min-width: unset; width: 100%; }

  /* Course card meta wrap */
  .course-card-meta { flex-wrap: wrap; gap: var(--space-sm); }

  /* Testimonial stars visible */
  .testimonial-stars { font-size: 1rem; }
}

/* ============================================
   17. RESPONSIVE — SMALL MOBILE (≤ 480px)
   ============================================ */
@media (max-width: 480px) {

  /* Container tight */
  .container, .container-sm { padding: 0 var(--space-md); }

  /* Typography very small */
  h1 { font-size: 1.7rem; line-height: 1.25; }
  h2 { font-size: 1.35rem; }
  h3 { font-size: 1.1rem; }

  /* Footer single col */
  .footer-grid { grid-template-columns: 1fr; }
  .footer-brand { grid-column: 1; }

  /* Buttons */
  .btn-lg { padding: 14px 22px; font-size: 1rem; }
  .btn { font-size: 0.9rem; padding: 10px 20px; }

  /* Hero */
  .hero-eyebrow { font-size: 0.8rem; padding: 5px 14px; }
  .hero-stat-num { font-size: 1.6rem; }
  .hero-stats { gap: var(--space-lg); }

  /* Sections */
  .section { padding: var(--space-2xl) 0; }

  /* Cards */
  .course-card-body { padding: var(--space-lg); }
  .blog-card-body { padding: var(--space-lg); }
  .stat-card { padding: var(--space-xl); }
  .stat-num { font-size: 2.2rem; }

  /* Trust bar */
  .trust-bar-inner { justify-content: flex-start; }
  .trust-item { font-size: 0.8rem; }

  /* Author box */
  .author-box { padding: var(--space-lg); }
  .author-avatar { width: 64px; height: 64px; }

  /* Breadcrumb */
  .breadcrumb { font-size: 0.78rem; }
  .breadcrumb-current {
    overflow: hidden; text-overflow: ellipsis;
    white-space: nowrap; max-width: 180px;
  }

  /* Floating cards hidden on very small screens */
  .floating-card { display: none; }

  /* Feature icon */
  .feature-icon { width: 48px; height: 48px; font-size: 1.4rem; }
}

/* ============================================
   18. PRINT STYLES
   ============================================ */
@media print {
  .site-header, .mobile-nav, .site-footer, .floating-card { display: none !important; }
  body { padding-top: 0; }
  .hero { min-height: auto; padding: var(--space-xl) 0; }
  a { color: #000; }
  pre { white-space: pre-wrap; }
}