/* ============================================================
   ITView — Deep Space Observatory Design System
   ============================================================ */

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

/* --- Theme Variables --- */
:root,
[data-theme="light"] {
  --bg-deep: #f0f2f5;
  --bg-gradient-start: #e8ecf1;
  --bg-gradient-end: #d5dce6;
  --surface-glass: rgba(255, 255, 255, 0.62);
  --surface-glass-strong: rgba(255, 255, 255, 0.82);
  --surface-glass-soft: rgba(255, 255, 255, 0.45);
  --glass-border: rgba(200, 210, 225, 0.65);
  --glass-shadow: 0 8px 32px rgba(15, 23, 42, 0.06);
  --glass-shadow-lg: 0 24px 64px rgba(15, 23, 42, 0.10);
  --glass-blur: 24px;
  --heading-color: #0f172a;
  --text-primary: #1e293b;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  --accent-primary: #2563eb;
  --accent-secondary: #0891b2;
  --accent-glow: rgba(37, 99, 235, 0.15);
  --accent-gradient: linear-gradient(135deg, #2563eb 0%, #0891b2 100%);
  --border-subtle: rgba(15, 23, 42, 0.08);
  --border-default: rgba(15, 23, 42, 0.12);
  --orb-1: rgba(37, 99, 235, 0.08);
  --orb-2: rgba(8, 145, 178, 0.06);
  --orb-3: rgba(124, 58, 237, 0.05);
  --code-bg: #f1f5f9;
  --code-border: #e2e8f0;
  --tag-bg: rgba(37, 99, 235, 0.08);
  --tag-color: #2563eb;
}

[data-theme="dark"] {
  --bg-deep: #0b1120;
  --bg-gradient-start: #0f1729;
  --bg-gradient-end: #0b1120;
  --surface-glass: rgba(30, 41, 59, 0.55);
  --surface-glass-strong: rgba(30, 41, 59, 0.78);
  --surface-glass-soft: rgba(30, 41, 59, 0.35);
  --glass-border: rgba(71, 85, 105, 0.45);
  --glass-shadow: 0 8px 32px rgba(0, 0, 0, 0.25);
  --glass-shadow-lg: 0 24px 64px rgba(0, 0, 0, 0.40);
  --glass-blur: 28px;
  --heading-color: #f1f5f9;
  --text-primary: #e2e8f0;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --accent-primary: #3b82f6;
  --accent-secondary: #22d3ee;
  --accent-glow: rgba(59, 130, 246, 0.20);
  --accent-gradient: linear-gradient(135deg, #3b82f6 0%, #22d3ee 100%);
  --border-subtle: rgba(255, 255, 255, 0.05);
  --border-default: rgba(255, 255, 255, 0.08);
  --orb-1: rgba(59, 130, 246, 0.12);
  --orb-2: rgba(34, 211, 238, 0.08);
  --orb-3: rgba(139, 92, 246, 0.07);
  --code-bg: #1e293b;
  --code-border: #334155;
  --tag-bg: rgba(59, 130, 246, 0.12);
  --tag-color: #60a5fa;
}

/* --- 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: 'Sora', 'Noto Sans SC', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  color: var(--text-primary);
  background: var(--bg-deep);
  line-height: 1.9;
  min-height: 100vh;
  overflow-x: hidden;
}

a {
  color: var(--accent-primary);
  text-decoration: none;
  transition: color 0.2s ease;
}

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

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

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 {
  color: var(--heading-color);
  font-family: 'Sora', 'Noto Sans SC', sans-serif;
  font-weight: 700;
  line-height: 1.3;
}

h1 { font-size: 2.5rem; letter-spacing: -0.02em; }
h2 { font-size: 1.875rem; letter-spacing: -0.015em; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }

code, pre, .mono {
  font-family: 'JetBrains Mono', 'Fira Code', monospace;
}

/* --- Container --- */
.site-container {
  max-width: 1320px;
  margin: 0 auto;
  padding: 0 2rem;
}

/* --- Glass Panel --- */
.glass {
  background: var(--surface-glass);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
  border-radius: 16px;
  box-shadow: var(--glass-shadow);
}

.glass-strong {
  background: var(--surface-glass-strong);
  backdrop-filter: blur(40px);
  -webkit-backdrop-filter: blur(40px);
  border: 1px solid var(--glass-border);
  border-radius: 16px;
  box-shadow: var(--glass-shadow-lg);
}

/* ============================================================
   NAVIGATION
   ============================================================ */
.site-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1100;
  padding: 0.75rem 0;
  transition: all 0.3s ease;
}

/* site-nav.scrolled styles moved to ENHANCED NAV SCROLL STATE section */

.nav-inner {
  max-width: 1320px;
  margin: 0 auto;
  padding: 0 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-family: 'Sora', sans-serif;
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--heading-color);
  text-decoration: none;
  letter-spacing: -0.02em;
}

.nav-brand:hover {
  color: var(--accent-primary);
}

.nav-brand-icon {
  width: 32px;
  height: 32px;
  background: var(--accent-gradient);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 0.875rem;
  font-weight: 800;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  list-style: none;
}

.nav-links a {
  display: block;
  padding: 0.5rem 1rem;
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 500;
  border-radius: 8px;
  transition: all 0.2s ease;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--accent-primary);
  background: var(--accent-glow);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.nav-search-btn,
.nav-theme-btn {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: none;
  background: transparent;
  color: var(--text-secondary);
  border-radius: 10px;
  cursor: pointer;
  font-size: 1.1rem;
  transition: all 0.2s ease;
}

.nav-search-btn:hover,
.nav-theme-btn:hover {
  background: var(--accent-glow);
  color: var(--accent-primary);
}

.nav-hamburger {
  display: none;
  width: 40px;
  height: 40px;
  align-items: center;
  justify-content: center;
  border: none;
  background: transparent;
  color: var(--text-primary);
  cursor: pointer;
  border-radius: 10px;
}

.nav-hamburger:hover {
  background: var(--accent-glow);
}

/* ============================================================
   MEGA DROPDOWN (jimmysong.io pattern)
   ============================================================ */
.mega-dropdown {
  position: relative;
}

.mega-toggle {
  display: flex;
  align-items: center;
  padding: 0.5rem 1rem;
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 500;
  border-radius: 8px;
  transition: all 0.2s ease;
  text-decoration: none;
}

.mega-toggle:hover,
.mega-dropdown:hover .mega-toggle {
  color: var(--accent-primary);
  background: var(--accent-glow);
}

.mega-menu {
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%) translateY(8px);
  max-width: 680px;
  width: calc(100vw - 2rem);
  padding-top: 0.75rem;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition: opacity 0.25s ease, visibility 0.25s ease, transform 0.25s ease;
  z-index: 1000;
}

.mega-dropdown:hover .mega-menu,
.mega-dropdown:focus-within .mega-menu {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(8px);
  pointer-events: auto;
}

.mega-menu-inner {
  background: var(--surface-glass-strong);
  backdrop-filter: blur(32px);
  -webkit-backdrop-filter: blur(32px);
  border: 1px solid var(--glass-border);
  border-radius: 16px;
  box-shadow: var(--glass-shadow-lg);
  overflow: hidden;
}

.mega-menu-content {
  padding: 1.5rem;
}

.mega-column-title {
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 1rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--border-subtle);
}

.mega-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.5rem;
}

.mega-link-item {
  display: block;
  padding: 0.75rem 1rem;
  border-radius: 10px;
  text-decoration: none;
  color: inherit;
  transition: all 0.2s ease;
}

.mega-link-item:hover {
  background: var(--accent-glow);
}

.mega-item-header {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 0.25rem;
}

.mega-item-icon {
  font-size: 0.95rem;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--accent-glow);
  color: var(--accent-primary);
  border-radius: 8px;
  flex-shrink: 0;
}

.mega-item-title {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--heading-color);
}

.mega-item-desc {
  font-size: 0.78rem;
  color: var(--text-muted);
  line-height: 1.5;
  margin: 0;
  padding-left: 2.75rem;
}

.mega-menu-footer {
  padding: 1rem 1.5rem;
  border-top: 1px solid var(--border-subtle);
}

.mega-footer-link {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--accent-primary);
  text-decoration: none;
  padding: 0.5rem 1.25rem;
  border-radius: 100px;
  background: var(--accent-glow);
  transition: all 0.2s ease;
}

.mega-footer-link:hover {
  background: var(--accent-primary);
  color: #ffffff;
}

/* Mobile: mega menu becomes full-width */
@media (max-width: 768px) {
  .mega-menu {
    position: static;
    transform: none;
    width: 100%;
    padding-top: 0.25rem;
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    display: none;
  }

  .mega-dropdown.open .mega-menu {
    display: block;
  }

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

/* Mobile Nav */
@media (max-width: 768px) {
  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    flex-direction: column;
    padding: 1rem;
    background: var(--surface-glass-strong);
    backdrop-filter: blur(32px);
    -webkit-backdrop-filter: blur(32px);
    border-bottom: 1px solid var(--glass-border);
    box-shadow: var(--glass-shadow-lg);
  }

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

  .nav-links a {
    width: 100%;
    padding: 0.75rem 1rem;
  }

  .nav-hamburger {
    display: flex;
  }
}

/* ============================================================
   HERO SECTION
   ============================================================ */
.hero {
  position: relative;
  min-height: 65vh;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  background: linear-gradient(160deg, var(--bg-gradient-start) 0%, var(--bg-gradient-end) 50%, var(--bg-deep) 100%);
  padding: 4rem 0;
}

.hero-bg {
  position: absolute;
  inset: 0;
  overflow: hidden;
  pointer-events: none;
}

/* Floating Orbs — base styles (animation overridden in ENHANCED HERO ORBS section) */
.hero-orb {
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
}

.hero-orb--1 {
  width: 500px;
  height: 500px;
  background: var(--orb-1);
  top: -10%;
  right: -5%;
}

.hero-orb--2 {
  width: 400px;
  height: 400px;
  background: var(--orb-2);
  bottom: -15%;
  left: -8%;
}

.hero-orb--3 {
  width: 300px;
  height: 300px;
  background: var(--orb-3);
  top: 40%;
  left: 50%;
}

/* Hero Grid Pattern */
.hero-grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--border-subtle) 1px, transparent 1px),
    linear-gradient(90deg, var(--border-subtle) 1px, transparent 1px);
  background-size: 60px 60px;
  opacity: 0.4;
  mask-image: radial-gradient(ellipse 80% 60% at 50% 40%, black 30%, transparent 70%);
  -webkit-mask-image: radial-gradient(ellipse 80% 60% at 50% 40%, black 30%, transparent 70%);
}

.hero-content {
  position: relative;
  z-index: 2;
  text-align: center;
  max-width: 800px;
  padding: 2rem 1.5rem;
  animation: hero-fade-in 1s ease-out;
}

@keyframes hero-fade-in {
  from { opacity: 0; transform: translateY(30px); }
  to { opacity: 1; transform: translateY(0); }
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.4rem 1rem;
  background: var(--tag-bg);
  color: var(--tag-color);
  border: 1px solid var(--accent-glow);
  border-radius: 100px;
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  margin-bottom: 2rem;
}

.hero-badge-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent-primary);
  animation: pulse-dot 2s ease-in-out infinite;
}

@keyframes pulse-dot {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.5; transform: scale(1.3); }
}

.hero-title {
  font-size: clamp(2.5rem, 6vw, 4.5rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.1;
  margin-bottom: 1.5rem;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: clamp(1rem, 2vw, 1.25rem);
  color: var(--text-secondary);
  font-weight: 400;
  margin-bottom: 1rem;
  line-height: 1.6;
}

.hero-tagline {
  font-size: 0.95rem;
  color: var(--text-muted);
  margin-bottom: 2.5rem;
}

.hero-tags {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.5rem;
  margin-bottom: 3rem;
}

.hero-tag {
  padding: 0.4rem 1rem;
  background: var(--surface-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--glass-border);
  border-radius: 100px;
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: all 0.25s ease;
}

.hero-tag:hover {
  border-color: var(--accent-primary);
  color: var(--accent-primary);
  background: var(--accent-glow);
  transform: translateY(-2px);
}

.hero-cta {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 1rem;
}

/* Buttons */
.btn-glass {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 2rem;
  border-radius: 100px;
  font-size: 1rem;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  border: none;
  text-decoration: none;
  position: relative;
  overflow: hidden;
}

/* jimmysong.io radial sheen effect on hover */
.btn-glass::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(255,255,255,0.25) 0%, transparent 70%);
  transform: translate(-50%, -50%);
  transition: width 0.5s ease, height 0.5s ease;
}

.btn-glass:hover::before {
  width: 300px;
  height: 300px;
}

.btn-glass:active {
  transform: translateY(2px) scale(0.98);
}

.btn-primary {
  background: var(--accent-gradient);
  color: #ffffff;
  box-shadow: 0 4px 16px var(--accent-glow);
}

.btn-primary:hover {
  box-shadow: 0 8px 32px var(--accent-glow);
  transform: translateY(-2px);
  color: #ffffff;
}

.btn-outline {
  background: var(--surface-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  color: var(--text-primary);
  border: 1px solid var(--glass-border);
}

.btn-outline:hover {
  border-color: var(--accent-primary);
  color: var(--accent-primary);
  background: var(--accent-glow);
  transform: translateY(-2px);
}

.btn-ghost {
  background: transparent;
  border: 1px solid var(--glass-border);
  color: var(--text-secondary);
  padding: 0.55rem 1.25rem;
  border-radius: 10px;
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s;
  font-family: inherit;
}
.btn-ghost:hover {
  background: var(--surface-glass-soft);
  color: var(--text-primary);
}

.btn-accent {
  background: linear-gradient(135deg, #f59e0b 0%, #ef4444 100%);
  border: none;
  color: #fff;
  padding: 0.55rem 1.25rem;
  border-radius: 10px;
  font-size: 0.875rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  font-family: inherit;
  box-shadow: 0 4px 12px rgba(245, 158, 11, 0.3);
}
.btn-accent:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(245, 158, 11, 0.4);
}

/* ============================================================
   QUIZ SYSTEM
   ============================================================ */
#quiz-overlay {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 9999;
  align-items: center;
  justify-content: center;
}
#quiz-overlay.open {
  display: flex;
}
.quiz-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.65);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
}
.quiz-card {
  position: relative;
  background: var(--surface-glass-strong);
  border: 1px solid var(--glass-border);
  border-radius: 20px;
  width: min(720px, calc(100vw - 2rem));
  max-height: calc(100vh - 4rem);
  overflow-y: auto;
  box-shadow: var(--glass-shadow-lg);
  display: flex;
  flex-direction: column;
}
.quiz-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.25rem 1.5rem 0.75rem;
  border-bottom: 1px solid var(--border-subtle);
  position: sticky;
  top: 0;
  background: inherit;
  z-index: 1;
  border-radius: 20px 20px 0 0;
}
.quiz-mode-label {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--accent-primary);
  letter-spacing: 0.02em;
}
.quiz-close {
  background: none;
  border: none;
  cursor: pointer;
  color: var(--text-muted);
  padding: 0.25rem;
  border-radius: 6px;
  display: flex;
  align-items: center;
  transition: color 0.15s, background 0.15s;
  line-height: 1;
}
.quiz-close:hover {
  color: var(--text-primary);
  background: var(--surface-glass-soft);
}
.quiz-progress-bar {
  height: 3px;
  background: var(--border-subtle);
  transition: width 0.4s ease;
}
.quiz-progress-bar::after {
  content: '';
  display: block;
  height: 100%;
  width: var(--pct, 0%);
  background: var(--accent-gradient);
  transition: width 0.4s ease;
}
.quiz-body {
  padding: 1.75rem 1.5rem 1rem;
  flex: 1;
}
.quiz-footer {
  padding: 0.75rem 1.5rem 1.25rem;
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 0.75rem;
  border-top: 1px solid var(--border-subtle);
}

/* Start screen */
.quiz-start {
  text-align: center;
  padding: 1rem 0 0.5rem;
}
.quiz-start-icon {
  font-size: 3rem;
  margin-bottom: 0.75rem;
  color: var(--accent-primary);
}
.quiz-start h3 {
  font-size: 1.375rem;
  color: var(--heading-color);
  margin-bottom: 0.5rem;
}
.quiz-start p {
  color: var(--text-secondary);
  font-size: 0.9375rem;
  line-height: 1.6;
}
.quiz-progress-note {
  margin-top: 0.5rem;
  font-size: 0.8125rem;
  color: var(--text-muted) !important;
}

/* Question text */
.quiz-question-text {
  font-size: 1rem;
  font-weight: 500;
  color: var(--heading-color);
  line-height: 1.65;
  margin-bottom: 1.25rem;
}
.quiz-reference-hint {
  font-size: 0.8125rem;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}
.quiz-reference-hint i { font-size: 0.875rem; }

/* Options */
.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 0.625rem;
}
.quiz-option {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  padding: 0.875rem 1rem;
  background: var(--surface-glass);
  border: 1px solid var(--glass-border);
  border-radius: 12px;
  cursor: pointer;
  transition: all 0.18s;
  text-align: left;
  font-family: inherit;
  color: var(--text-primary);
  font-size: 0.9375rem;
  line-height: 1.5;
}
.quiz-option:hover:not(:disabled) {
  border-color: var(--accent-primary);
  background: var(--accent-glow);
  transform: translateX(4px);
}
.quiz-option.selected { border-color: var(--accent-primary); background: var(--accent-glow); }
.quiz-option.correct { border-color: #10b981 !important; background: rgba(16, 185, 129, 0.1) !important; }
.quiz-option.wrong { border-color: #ef4444 !important; background: rgba(239, 68, 68, 0.08) !important; }
.quiz-option:disabled { cursor: default; }
.quiz-option-letter {
  flex-shrink: 0;
  width: 1.75rem;
  height: 1.75rem;
  background: var(--surface-glass-strong);
  border: 1px solid var(--glass-border);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--accent-primary);
}
.quiz-option.correct .quiz-option-letter { background: #10b981; color: #fff; border-color: #10b981; }
.quiz-option.wrong .quiz-option-letter { background: #ef4444; color: #fff; border-color: #ef4444; }
.quiz-option-text { flex: 1; }

/* Explanation */
.quiz-explanation {
  margin-top: 1rem;
  padding: 0.875rem 1rem;
  background: var(--surface-glass-soft);
  border-left: 3px solid var(--accent-primary);
  border-radius: 0 8px 8px 0;
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.65;
}
.quiz-explanation strong { color: var(--heading-color); }

/* Score ring */
.quiz-result {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 1.5rem 0 0.5rem;
  gap: 1.25rem;
}
.quiz-score-ring {
  position: relative;
  width: 120px;
  height: 120px;
}
.quiz-score-ring svg { transform: rotate(-90deg); }
.ring-bg {
  fill: none;
  stroke: var(--border-subtle);
  stroke-width: 10;
}
.ring-fill {
  fill: none;
  stroke: var(--accent-gradient);
  stroke-width: 10;
  stroke-linecap: round;
  transition: stroke-dashoffset 1s ease;
}
.ring-label {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.1rem;
}
.ring-num {
  font-size: 2rem;
  font-weight: 700;
  color: var(--heading-color);
}
.ring-den { font-size: 0.875rem; color: var(--text-muted); align-self: flex-end; padding-bottom: 0.35rem; }
.quiz-result-text { color: var(--text-secondary); font-size: 1rem; }

/* Loading / Empty / Error states */
.quiz-loading {
  text-align: center;
  padding: 2.5rem 1rem;
  color: var(--text-secondary);
  font-size: 0.9375rem;
}
.quiz-loading i { display: block; font-size: 1.75rem; margin-bottom: 0.75rem; color: var(--accent-primary); }
.quiz-empty {
  text-align: center;
  padding: 2.5rem 1rem;
  color: var(--text-muted);
  font-size: 0.9375rem;
}
.quiz-error {
  text-align: center;
  padding: 1.25rem;
  background: rgba(239, 68, 68, 0.06);
  border: 1px solid rgba(239, 68, 68, 0.2);
  border-radius: 12px;
  color: #ef4444;
}
.quiz-error i { font-size: 1.5rem; display: block; margin-bottom: 0.5rem; }
.quiz-error p { font-size: 0.875rem; }

/* Textarea */
.quiz-textarea {
  width: 100%;
  min-height: 140px;
  padding: 0.875rem 1rem;
  background: var(--surface-glass);
  border: 1px solid var(--glass-border);
  border-radius: 12px;
  color: var(--text-primary);
  font-size: 0.9375rem;
  line-height: 1.65;
  font-family: inherit;
  resize: vertical;
  transition: border-color 0.2s;
  margin-bottom: 0.75rem;
}
.quiz-textarea:focus {
  outline: none;
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px var(--accent-glow);
}
.quiz-textarea.error {
  border-color: #ef4444;
  animation: shake 0.3s;
}
@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-6px); }
  75% { transform: translateX(6px); }
}
.quiz-textarea::placeholder { color: var(--text-muted); }

/* Eval result */
.quiz-eval-result {
  margin-top: 0.75rem;
}
.quiz-score-mini {
  display: flex;
  align-items: baseline;
  gap: 0.25rem;
  margin-bottom: 0.875rem;
}
.qsm-num {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--score-color, var(--accent-primary));
}
.qsm-den { font-size: 1rem; color: var(--text-muted); }
.quiz-feedback {
  font-size: 0.9375rem;
  color: var(--text-primary);
  line-height: 1.65;
  margin-bottom: 0.875rem;
}
.quiz-kw-section { margin-bottom: 0.625rem; }
.quiz-kw-section label {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  display: block;
  margin-bottom: 0.4rem;
}
.quiz-kw-list { display: flex; flex-wrap: wrap; gap: 0.4rem; }
.kw {
  padding: 0.2rem 0.6rem;
  border-radius: 6px;
  font-size: 0.8125rem;
  font-weight: 500;
}
.kw-found { background: rgba(16, 185, 129, 0.12); color: #10b981; }
.kw-missed { background: rgba(239, 68, 68, 0.1); color: #ef4444; }
.quiz-suggestion label {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  display: block;
  margin-bottom: 0.35rem;
}
.quiz-suggestion p { font-size: 0.875rem; color: var(--text-secondary); line-height: 1.65; }

/* Question list in eval picker */
.quiz-question-list {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  margin-top: 1rem;
  max-height: 360px;
  overflow-y: auto;
}
.quiz-question-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem 1rem;
  background: var(--surface-glass);
  border: 1px solid var(--glass-border);
  border-radius: 10px;
  cursor: pointer;
  transition: all 0.18s;
  text-align: left;
  font-family: inherit;
}
.quiz-question-item:hover { border-color: var(--accent-primary); background: var(--accent-glow); }
.quiz-question-item.done { opacity: 0.6; }
.quiz-question-item .done-icon { color: #10b981; margin-left: auto; }
.quiz-q-num {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--accent-primary);
  background: var(--accent-glow);
  padding: 0.2rem 0.5rem;
  border-radius: 6px;
  flex-shrink: 0;
}
.quiz-q-title {
  font-size: 0.875rem;
  color: var(--text-primary);
  flex: 1;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

/* Dark theme overrides for quiz */
[data-theme="dark"] .quiz-card {
  background: rgba(15, 23, 42, 0.85);
}
[data-theme="dark"] .quiz-question-item,
[data-theme="dark"] .quiz-option,
[data-theme="dark"] .quiz-textarea {
  background: rgba(30, 41, 59, 0.6);
}
[data-theme="dark"] .quiz-option.correct { background: rgba(16, 185, 129, 0.08) !important; }
[data-theme="dark"] .quiz-option.wrong { background: rgba(239, 68, 68, 0.06) !important; }
[data-theme="dark"] .quiz-start-icon { color: #60a5fa; }

/* ============================================================
   SECTION COMMON
   ============================================================ */
.site-section {
  position: relative;
  padding: 5rem 0;
}

/* ::after — 渐变发光线分割线（顶部，从中心向两侧淡出） */
.site-section::after {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent 0%, var(--section-divider-color, rgba(148, 197, 255, 0.18)) 50%, transparent 100%);
  pointer-events: none;
}

/* ::before — 左上角径向环境光晕 */
.site-section::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: radial-gradient(
    140% 90% at 12% 0%,
    var(--section-glow-color, rgba(59, 130, 246, 0.08)),
    transparent 58%
  );
  z-index: 0;
}

.site-section > * {
  position: relative;
  z-index: 1;
}

/* 各板块独立色彩 — Stats: blue */
.site-section[data-divider-color="#3b82f6"] {
  --section-divider-color: #3b82f6;
  --section-glow-color: rgba(59, 130, 246, 0.08);
}

/* Interview: cyan */
.site-section[data-divider-color="#22d3ee"] {
  --section-divider-color: #22d3ee;
  --section-glow-color: rgba(34, 211, 238, 0.08);
}

/* Blog: violet */
.site-section[data-divider-color="#a78bfa"] {
  --section-divider-color: #a78bfa;
  --section-glow-color: rgba(167, 139, 250, 0.08);
}

/* Books: pink */
.site-section[data-divider-color="#f472b6"] {
  --section-divider-color: #f472b6;
  --section-glow-color: rgba(244, 114, 182, 0.08);
}

/* About: sky */
.site-section[data-divider-color="#38bdf8"] {
  --section-divider-color: #38bdf8;
  --section-glow-color: rgba(56, 189, 248, 0.08);
}

/* 亮色模式：增强分割线与光晕对比度 */
[data-theme="light"] .site-section[data-divider-color="#3b82f6"] {
  --section-divider-color: rgba(37, 99, 235, 0.55);
  --section-glow-color: rgba(37, 99, 235, 0.06);
}

[data-theme="light"] .site-section[data-divider-color="#22d3ee"] {
  --section-divider-color: rgba(6, 182, 212, 0.55);
  --section-glow-color: rgba(6, 182, 212, 0.06);
}

[data-theme="light"] .site-section[data-divider-color="#a78bfa"] {
  --section-divider-color: rgba(139, 92, 246, 0.50);
  --section-glow-color: rgba(139, 92, 246, 0.05);
}

[data-theme="light"] .site-section[data-divider-color="#f472b6"] {
  --section-divider-color: rgba(236, 72, 153, 0.50);
  --section-glow-color: rgba(236, 72, 153, 0.05);
}

[data-theme="light"] .site-section[data-divider-color="#38bdf8"] {
  --section-divider-color: rgba(14, 165, 233, 0.55);
  --section-glow-color: rgba(14, 165, 233, 0.06);
}

.section-header {
  text-align: center;
  margin-bottom: 3rem;
}

.section-label {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent-primary);
  margin-bottom: 0.75rem;
}

.section-title {
  font-size: 2rem;
  margin-bottom: 0.75rem;
}

.section-desc {
  font-size: 1.05rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

/* ============================================================
   CATEGORY CARDS
   ============================================================ */
.category-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.25rem;
}

.category-card {
  background: var(--surface-glass);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
  border-radius: 16px;
  padding: 1.75rem;
  text-decoration: none;
  color: inherit;
  transition: all 0.35s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
  overflow: hidden;
}

.category-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--accent-gradient);
  opacity: 0;
  transition: opacity 0.3s ease;
}

/* jimmysong.io hover-shadow pattern */
.category-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.12), 0 0 0 1px var(--accent-primary);
  border-color: var(--accent-primary);
}

[data-theme="dark"] .category-card:hover {
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.35), 0 0 0 1px var(--accent-primary);
}

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

.category-card-icon {
  font-size: 1.5rem;
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--accent-glow);
  color: var(--accent-primary);
  border-radius: 12px;
  margin-bottom: 1rem;
}

.category-card-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--heading-color);
  margin-bottom: 0.5rem;
}

.category-card-desc {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 1rem;
}

.category-card-count {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent-primary);
}

/* ============================================================
   STATS ROW
   ============================================================ */
.stats-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1.25rem;
  margin-top: 2rem;
}

.stat-card {
  text-align: center;
  padding: 2rem 1.5rem;
  background: var(--surface-glass);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
  border-radius: 16px;
}

/* stat-number styles moved to STAT NUMBER COUNTER ANIMATION section */

/* ============================================================
   BOOK SHELF (Placeholder)
   ============================================================ */
.bookshelf {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 1.5rem;
}

.book-card {
  background: var(--surface-glass);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
  border-radius: 12px;
  overflow: hidden;
  transition: all 0.3s ease;
}

.book-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--glass-shadow-lg);
}

.book-card-cover {
  aspect-ratio: 3/4;
  background: linear-gradient(135deg, var(--accent-glow), var(--surface-glass-soft));
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 3rem;
}

.book-card-info {
  padding: 1rem;
}

.book-card-title {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--heading-color);
  margin-bottom: 0.25rem;
}

.book-card-meta {
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* Placeholder state */
.placeholder-card {
  border-style: dashed;
  opacity: 0.6;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 260px;
  font-size: 1rem;
  color: var(--text-muted);
}

/* ============================================================
   BLOG CARDS (Placeholder)
   ============================================================ */
.blog-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 1.5rem;
}

.blog-card {
  background: var(--surface-glass);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
  border-radius: 16px;
  padding: 1.75rem;
  transition: all 0.3s ease;
  text-decoration: none;
  color: inherit;
}

.blog-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--glass-shadow-lg);
  border-color: var(--accent-primary);
}

.blog-card-date {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
}

.blog-card-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--heading-color);
  margin-bottom: 0.5rem;
  line-height: 1.4;
}

.blog-card-excerpt {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* ============================================================
   ABOUT SECTION
   ============================================================ */
.about-section {
  display: grid;
  grid-template-columns: 1fr 280px;
  gap: 3rem;
  align-items: center;
}

.about-text h2 {
  margin-bottom: 1rem;
}

.about-text p {
  color: var(--text-secondary);
  margin-bottom: 1rem;
  font-size: 1.05rem;
}

.about-avatar {
  width: 280px;
  height: 280px;
  border-radius: 24px;
  background: var(--surface-glass);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 2px solid var(--glass-border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 5rem;
  position: relative;
  overflow: hidden;
}

.about-avatar::after {
  content: '';
  position: absolute;
  inset: -2px;
  border-radius: inherit;
  background: var(--accent-gradient);
  opacity: 0.15;
}

@media (max-width: 768px) {
  .about-section {
    grid-template-columns: 1fr;
    text-align: center;
  }
  .about-avatar {
    margin: 0 auto;
    order: -1;
  }
}

/* ============================================================
   BREADCRUMB (jimmysong.io pill style)
   ============================================================ */
.breadcrumb-nav {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
}

.breadcrumb-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.4rem 1rem;
  border-radius: 100px;
  font-size: 0.82rem;
  font-weight: 600;
  text-decoration: none;
  transition: all 0.2s ease;
}

.breadcrumb-pill i {
  font-size: 0.75rem;
}

.breadcrumb-home {
  background: var(--accent-primary);
  color: #ffffff;
}

.breadcrumb-home:hover {
  background: var(--accent-hover, #1d4ed8);
  color: #ffffff;
  transform: translateY(-1px);
}

.breadcrumb-category {
  background: var(--accent-primary);
  color: #ffffff;
}

.breadcrumb-category:hover {
  background: var(--accent-hover, var(--accent-primary));
  color: #ffffff;
  transform: translateY(-1px);
}

.breadcrumb-sub {
  background: var(--accent-secondary);
  color: #ffffff;
}

.breadcrumb-sub:hover {
  background: var(--accent-secondary-hover, var(--accent-secondary));
  color: #ffffff;
  transform: translateY(-1px);
}

.breadcrumb-current {
  background: var(--surface-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--glass-border);
  color: var(--text-secondary);
}

/* ============================================================
   PRODUCT PAGE (jimmysong.io book detail pattern)
   ============================================================ */
.product-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
}

.product-header h1 {
  margin: 0;
}

.question-count-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--accent-primary);
  background: var(--tag-bg);
  padding: 0.3rem 0.85rem;
  border-radius: 100px;
}

/* Product info card — jimmysong.io book-info-card */
.product-info-card {
  background: var(--surface-glass);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
  border-radius: 12px;
  padding: 1rem 1.25rem;
  margin-bottom: 1.5rem;
}

.product-info-list {
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
  margin: 0;
}

.product-info-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.product-info-item dt {
  font-size: 0.8rem;
  color: var(--text-muted);
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: 0.3rem;
}

.product-info-item dt i {
  font-size: 0.75rem;
  color: var(--accent-primary);
}

.product-info-item dd {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--heading-color);
  margin: 0;
}

/* Three-column product layout */
.product-layout {
  display: grid;
  grid-template-columns: 220px 1fr 260px;
  gap: 1.5rem;
  transition: opacity 0.3s ease;
}

.product-layout.toc-collapsed {
  grid-template-columns: 0px 1fr 260px;
}

.product-layout.sidebar-collapsed {
  grid-template-columns: 220px 1fr 0px;
}

.product-layout.toc-collapsed.sidebar-collapsed {
  grid-template-columns: 0px 1fr 0px;
}

.product-toc {
  position: sticky;
  top: 90px;
  max-height: calc(100vh - 110px);
  overflow: visible;
  transition: opacity 0.3s ease, width 0.3s ease;
}

.product-toc.collapsed {
  opacity: 0;
  width: 0;
  overflow: hidden;
  pointer-events: none;
}

.toc-toggle {
  position: absolute;
  top: 0;
  right: -40px;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--glass-border);
  background: var(--surface-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-radius: 8px;
  color: var(--text-secondary);
  cursor: pointer;
  font-size: 0.8rem;
  z-index: 10;
  transition: all 0.2s ease;
}

.toc-toggle:hover {
  background: var(--accent-glow);
  color: var(--accent-primary);
  border-color: var(--accent-primary);
}

.product-toc.collapsed + .toc-toggle,
.toc-collapsed .toc-toggle {
  right: 0;
}

.product-toc-card {
  background: var(--surface-glass);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
  border-radius: 12px;
  padding: 1rem;
  max-height: calc(100vh - 120px);
  overflow-y: auto;
}

.product-toc-title {
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.product-toc-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
}

.product-toc-item {
  display: flex;
  align-items: flex-start;
  gap: 0.5rem;
  padding: 0.35rem 0.5rem;
  border-radius: 6px;
  text-decoration: none;
  color: var(--text-secondary);
  font-size: 0.78rem;
  line-height: 1.4;
  transition: all 0.15s ease;
}

.product-toc-item:hover {
  background: var(--accent-glow);
  color: var(--accent-primary);
}

.product-toc-num {
  flex-shrink: 0;
  width: 20px;
  height: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--tag-bg);
  color: var(--tag-color);
  border-radius: 5px;
  font-size: 0.65rem;
  font-weight: 700;
  font-family: 'JetBrains Mono', monospace;
}

.product-toc-text {
  flex: 1;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.product-main {
  min-width: 0;
}

.product-sidebar {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  position: sticky;
  top: 90px;
  max-height: calc(100vh - 110px);
  overflow-y: auto;
  align-self: flex-start;
  transition: opacity 0.3s ease;
}

.product-sidebar.collapsed {
  opacity: 0;
  overflow: hidden;
  pointer-events: none;
}

.sidebar-toggle-btn {
  position: absolute;
  top: 0;
  left: -40px;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--glass-border);
  background: var(--surface-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-radius: 8px;
  color: var(--text-secondary);
  cursor: pointer;
  font-size: 0.8rem;
  z-index: 10;
  transition: all 0.2s ease;
}

.sidebar-toggle-btn:hover {
  background: var(--accent-glow);
  color: var(--accent-primary);
  border-color: var(--accent-primary);
}

.product-sidebar.collapsed + .sidebar-toggle-btn,
.sidebar-collapsed .sidebar-toggle-btn {
  left: 0;
}

/* Responsive: three-column → two-column → single */
@media (max-width: 1200px) {
  .product-layout {
    grid-template-columns: 180px 1fr 220px;
    gap: 1rem;
  }
}

@media (max-width: 992px) {
  .product-layout {
    grid-template-columns: 1fr;
  }

  .product-toc {
    display: none;
  }

  .product-sidebar {
    order: -1;
    flex-direction: row;
    overflow-x: auto;
    gap: 0.75rem;
  }

  .product-sidebar .sidebar-card {
    min-width: 220px;
    flex-shrink: 0;
  }
}

/* ============================================================
   LIST PAGE (jimmysong.io book page pattern)
   ============================================================ */
.list-layout {
  display: grid;
  grid-template-columns: 1fr 230px;
  gap: 2rem;
  margin-top: 2rem;
}

.list-main {
  min-width: 0;
}

.post-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.15rem;
}

.post-card {
  background: var(--surface-glass);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
  border-left: 3px solid var(--category-accent, var(--accent-primary));
  border-radius: 12px;
  text-decoration: none;
  color: inherit;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  display: block;
}

.post-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.1);
  border-left-color: var(--category-accent, var(--accent-primary));
}

[data-theme="dark"] .post-card:hover {
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.3);
}

.post-card-body {
  padding: 1.2rem 1.35rem;
}

.post-card-title {
  font-size: 0.98rem;
  font-weight: 700;
  color: var(--heading-color);
  margin-bottom: 0.4rem;
  line-height: 1.35;
}

.featured-star {
  color: #f59e0b;
  font-size: 0.85rem;
  margin-right: 0.25rem;
}

.post-card-meta {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-bottom: 0.4rem;
}

.post-card-meta-item {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
}

.post-card-meta-item i {
  font-size: 0.7rem;
}

.post-card-meta-sep {
  color: var(--text-muted);
  opacity: 0.5;
}

.post-card-meta-tag {
  display: inline-flex;
  align-items: center;
  padding: 0.15rem 0.6rem;
  border-radius: 100px;
  font-size: 0.72rem;
  font-weight: 600;
  background: color-mix(in srgb, var(--tag-color, #3b82f6) 12%, transparent);
  color: var(--tag-color, #3b82f6);
}

.post-card-excerpt {
  font-size: 0.82rem;
  color: var(--text-muted);
  line-height: 1.5;
  margin: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

/* Sidebar */
.list-sidebar {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  align-self: flex-start;
}

.sidebar-card {
  background: var(--surface-glass);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
  border-radius: 12px;
  padding: 1.25rem;
}

.sidebar-header {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 1rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--border-subtle);
}

.sidebar-reset {
  margin-left: auto;
  color: var(--text-muted);
  font-size: 0.75rem;
  transition: color 0.2s ease;
}

.sidebar-reset:hover {
  color: var(--accent-primary);
}

.sidebar-toggle {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 0.75rem;
  margin-bottom: 0.75rem;
  border-radius: 8px;
  cursor: pointer;
  font-size: 0.85rem;
  color: var(--text-secondary);
  transition: all 0.2s ease;
}

.sidebar-toggle:hover {
  background: var(--accent-glow);
}

.sidebar-toggle input[type="checkbox"] {
  accent-color: var(--accent-primary);
  width: 16px;
  height: 16px;
}

.sidebar-toggle-label {
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.sidebar-stats {
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: 1rem;
}

.sidebar-stats strong {
  color: var(--accent-primary);
  font-weight: 700;
}

.sidebar-categories {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.sidebar-cat-item {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.5rem 0.75rem;
  border-radius: 8px;
  text-decoration: none;
  color: var(--text-secondary);
  font-size: 0.85rem;
  transition: all 0.2s ease;
}

.sidebar-cat-item:hover,
.sidebar-cat-item.active {
  background: var(--accent-glow);
  color: var(--accent-primary);
}

.sidebar-cat-btn {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.5rem 0.75rem;
  border-radius: 8px;
  border: none;
  background: transparent;
  color: var(--text-secondary);
  font-size: 0.85rem;
  font-family: inherit;
  cursor: pointer;
  width: 100%;
  text-align: left;
  transition: all 0.2s ease;
}

.sidebar-cat-btn:hover {
  background: var(--accent-glow);
  color: var(--accent-primary);
}

.sidebar-cat-btn.active {
  background: var(--accent-glow);
  color: var(--accent-primary);
  font-weight: 600;
}

.sidebar-divider {
  height: 1px;
  background: var(--border-subtle);
  margin: 0.75rem 0;
}

.sidebar-filter-chip {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.4rem 0.9rem;
  border-radius: 100px;
  border: 1px solid var(--glass-border);
  background: transparent;
  color: var(--text-secondary);
  font-size: 0.8rem;
  font-weight: 500;
  font-family: inherit;
  cursor: pointer;
  transition: all 0.2s ease;
  margin-bottom: 0.75rem;
}

.sidebar-filter-chip:hover {
  border-color: var(--accent-primary);
  color: var(--accent-primary);
}

.sidebar-filter-chip.active {
  background: var(--accent-glow);
  border-color: var(--accent-primary);
  color: var(--accent-primary);
  font-weight: 600;
}

.sidebar-section-title {
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

.sidebar-cat-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  flex-shrink: 0;
}

.sidebar-cat-name {
  flex: 1;
}

.sidebar-cat-count {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  background: var(--surface-glass-soft);
  padding: 0.1rem 0.5rem;
  border-radius: 100px;
}

.sidebar-stat-list {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.sidebar-stat-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.sidebar-stat-row strong {
  color: var(--heading-color);
  font-weight: 700;
}

/* Pagination */
.pagination {
  display: flex;
  justify-content: center;
  gap: 0.4rem;
  margin-top: 1.5rem;
  padding: 1rem 0;
}

.pagination-item {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 8px;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
  background: var(--surface-glass);
  border: 1px solid var(--glass-border);
  text-decoration: none;
  transition: all 0.2s ease;
}

.pagination-item:hover {
  border-color: var(--accent-primary);
  color: var(--accent-primary);
  background: var(--accent-glow);
}

.pagination-item.active {
  background: var(--accent-primary);
  color: #ffffff;
  border-color: var(--accent-primary);
}

/* Responsive: stack on mobile */
@media (max-width: 992px) {
  .list-layout {
    grid-template-columns: 1fr;
  }

  .list-sidebar {
    order: -1;
    flex-direction: row;
    overflow-x: auto;
    gap: 0.75rem;
  }

  .sidebar-card {
    min-width: 240px;
    flex-shrink: 0;
  }
}

@media (max-width: 640px) {
  .post-grid {
    grid-template-columns: 1fr;
  }
}

/* ============================================================
   FOOTER
   ============================================================ */
.site-footer {
  padding: 4rem 0 2rem;
  border-top: 1px solid var(--border-default);
  margin-top: 2rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr repeat(3, 1fr);
  gap: 3rem;
  margin-bottom: 3rem;
}

.footer-brand-desc {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-top: 0.75rem;
  line-height: 1.7;
}

.footer-col-title {
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.footer-links {
  list-style: none;
}

.footer-links li {
  margin-bottom: 0.5rem;
}

.footer-links a {
  color: var(--text-secondary);
  font-size: 0.9rem;
  transition: color 0.2s ease;
}

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

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 2rem;
  border-top: 1px solid var(--border-subtle);
  font-size: 0.85rem;
  color: var(--text-muted);
}

.footer-social {
  display: flex;
  gap: 1rem;
}

.footer-social a {
  color: var(--text-muted);
  font-size: 1.2rem;
  transition: color 0.2s ease;
}

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

@media (max-width: 768px) {
  .footer-grid {
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
  }
  .footer-bottom {
    flex-direction: column;
    gap: 1rem;
    text-align: center;
  }
}

/* ============================================================
   SEARCH MODAL
   ============================================================ */
.search-modal {
  position: fixed;
  inset: 0;
  z-index: 2000;
  display: none;
  align-items: flex-start;
  justify-content: center;
  padding-top: 15vh;
}

.search-modal.open {
  display: flex;
}

.search-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
}

.search-dialog {
  position: relative;
  width: 100%;
  max-width: 640px;
  background: var(--surface-glass-strong);
  backdrop-filter: blur(32px);
  -webkit-backdrop-filter: blur(32px);
  border: 1px solid var(--glass-border);
  border-radius: 20px;
  box-shadow: var(--glass-shadow-lg);
  overflow: hidden;
  animation: search-slide-in 0.25s ease-out;
}

@keyframes search-slide-in {
  from { opacity: 0; transform: translateY(-20px) scale(0.97); }
  to { opacity: 1; transform: translateY(0) scale(1); }
}

.search-input-wrapper {
  display: flex;
  align-items: center;
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--border-subtle);
  gap: 0.75rem;
}

.search-input-wrapper i {
  color: var(--text-muted);
  font-size: 1.1rem;
}

.search-input {
  flex: 1;
  border: none;
  background: transparent;
  font-size: 1.1rem;
  font-family: inherit;
  color: var(--text-primary);
  outline: none;
}

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

.search-kbd {
  font-size: 0.7rem;
  font-family: 'JetBrains Mono', monospace;
  padding: 0.2rem 0.5rem;
  background: var(--surface-glass-soft);
  border: 1px solid var(--glass-border);
  border-radius: 6px;
  color: var(--text-muted);
}

.search-results {
  max-height: 50vh;
  overflow-y: auto;
  padding: 0.5rem;
}

.search-result-item {
  display: block;
  padding: 0.75rem 1rem;
  border-radius: 10px;
  text-decoration: none;
  color: inherit;
  transition: background 0.15s ease;
}

.search-result-item:hover {
  background: var(--accent-glow);
}

.search-result-header {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.search-result-title {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--heading-color);
}

.search-result-cat {
  font-size: 0.7rem;
  padding: 0.15rem 0.5rem;
  border-radius: 99px;
  background: var(--accent-glow);
  color: var(--accent-primary);
  font-weight: 500;
  white-space: nowrap;
}

.search-result-desc {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 0.2rem;
}

.search-result-questions {
  margin-top: 0.35rem;
  padding-left: 0.5rem;
  border-left: 2px solid var(--border-subtle);
}

.search-result-q {
  font-size: 0.78rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.search-empty {
  text-align: center;
  padding: 2rem 1rem;
  color: var(--text-muted);
  font-size: 0.9rem;
}

/* ============================================================
   INTERVIEW: ACCORDION
   ============================================================ */
.interview-header {
  padding: 6rem 0 1.5rem;
}

.interview-progress {
  margin-top: 1.5rem;
}

.progress-bar-wrapper {
  background: var(--surface-glass-soft);
  border-radius: 100px;
  height: 8px;
  overflow: hidden;
  margin-top: 0.5rem;
}

.progress-bar-fill {
  height: 100%;
  background: var(--accent-gradient);
  border-radius: 100px;
  transition: width 0.4s ease;
}

.progress-text {
  font-size: 0.8rem;
  color: var(--text-muted);
  font-weight: 500;
}

.accordion-controls {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
}

.btn-sm {
  padding: 0.4rem 1rem;
  font-size: 0.8rem;
  border-radius: 8px;
}

.accordion-panel {
  scroll-margin-top: 80px;
  background: var(--surface-glass);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
  border-radius: 12px;
  margin-bottom: 0.75rem;
  overflow: hidden;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.accordion-panel[open] {
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 1px var(--accent-glow);
}

.accordion-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 1rem 1.25rem;
  cursor: pointer;
  list-style: none;
  font-weight: 500;
  color: var(--text-primary);
  transition: background 0.2s ease;
}

.accordion-header::-webkit-details-marker { display: none; }
.accordion-header::marker { display: none; content: ''; }

.accordion-header:hover {
  background: var(--accent-glow);
}

.accordion-number {
  flex-shrink: 0;
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--tag-bg);
  color: var(--tag-color);
  border-radius: 8px;
  font-size: 0.75rem;
  font-weight: 700;
  font-family: 'JetBrains Mono', monospace;
}

.accordion-title {
  flex: 1;
  font-size: 0.95rem;
}

.accordion-icon {
  flex-shrink: 0;
  width: 20px;
  height: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-muted);
  transition: transform 0.25s ease;
}

details[open] > .accordion-header .accordion-icon {
  transform: rotate(180deg);
}

.accordion-body {
  padding: 0 1.25rem 1.5rem;
  border-top: 1px solid var(--border-subtle);
}

.accordion-body > *:first-child {
  margin-top: 1.25rem;
}

/* Content styling inside accordion */
.accordion-body h3 {
  font-size: 1.1rem;
  margin: 1.5rem 0 0.75rem;
  color: var(--heading-color);
}

.accordion-body h4 {
  font-size: 1rem;
  margin: 1.25rem 0 0.5rem;
}

.accordion-body p {
  color: var(--text-secondary);
  margin-bottom: 0.75rem;
  line-height: 1.8;
}

.accordion-body ul,
.accordion-body ol {
  padding-left: 1.5rem;
  margin-bottom: 1rem;
  color: var(--text-secondary);
}

.accordion-body li {
  margin-bottom: 0.35rem;
  line-height: 1.7;
}

.accordion-body strong {
  color: var(--heading-color);
  font-weight: 600;
}

.accordion-body table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0;
  font-size: 0.85rem;
}

.accordion-body th,
.accordion-body td {
  padding: 0.6rem 0.75rem;
  border: 1px solid var(--border-default);
  text-align: left;
}

.accordion-body th {
  background: var(--tag-bg);
  font-weight: 600;
  color: var(--heading-color);
}

.accordion-body td {
  color: var(--text-secondary);
}

/* Code blocks */
.accordion-body pre,
.accordion-body code {
  font-family: 'JetBrains Mono', 'Fira Code', monospace;
  font-size: 0.85rem;
}

.accordion-body pre {
  background: var(--code-bg);
  border: 1px solid var(--code-border);
  border-radius: 10px;
  padding: 1rem 1.25rem;
  overflow-x: auto;
  margin: 1rem 0;
  line-height: 1.6;
}

.accordion-body :not(pre) > code {
  background: var(--code-bg);
  border: 1px solid var(--code-border);
  border-radius: 5px;
  padding: 0.15rem 0.4rem;
  font-size: 0.85em;
  color: var(--accent-primary);
}

/* ============================================================
   PRODUCT GRID (Category pages)
   ============================================================ */
.product-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1.25rem;
}

.product-card {
  background: var(--surface-glass);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
  border-radius: 14px;
  padding: 1.5rem;
  text-decoration: none;
  color: inherit;
  transition: all 0.35s cubic-bezier(0.4, 0, 0.2, 1);
  display: flex;
  flex-direction: column;
}

.product-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--glass-shadow-lg);
  border-color: var(--accent-primary);
}

[data-theme="dark"] .product-card:hover {
  box-shadow: 0 16px 32px rgba(0, 0, 0, 0.3), 0 0 0 1px var(--accent-primary);
}

.product-card-title {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--heading-color);
  margin-bottom: 0.5rem;
}

.product-card-count {
  font-size: 0.8rem;
  color: var(--accent-primary);
  font-weight: 600;
}

/* ============================================================
   MERMAID ZOOM OVERLAY
   ============================================================ */
.mermaid {
  cursor: zoom-in;
  transition: transform 0.2s ease;
}

.mermaid:hover {
  transform: scale(1.01);
}

.mermaid-overlay {
  position: fixed;
  inset: 0;
  z-index: 2000;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(0, 0, 0, 0.75);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  cursor: zoom-out;
  padding: 2rem;
  animation: fadeIn 0.2s ease;
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.mermaid-overlay-inner {
  background: var(--surface-glass-strong);
  border: 1px solid var(--glass-border);
  border-radius: 16px;
  padding: 2rem;
  max-width: 90vw;
  max-height: 85vh;
  overflow: auto;
}

.mermaid-overlay-inner svg {
  width: 100%;
  height: auto;
  min-width: 500px;
}

.mermaid-overlay-close {
  position: absolute;
  top: 1rem;
  right: 1.5rem;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: none;
  background: rgba(255, 255, 255, 0.15);
  color: white;
  font-size: 1.5rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.2s ease;
  z-index: 1;
}

.mermaid-overlay-close:hover {
  background: rgba(255, 255, 255, 0.3);
}

/* ============================================================
   SCROLLBAR
   ============================================================ */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: var(--text-muted);
  border-radius: 3px;
  border: 1px solid transparent;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--text-secondary);
}

::-webkit-scrollbar-corner {
  background: transparent;
}

/* Code blocks: slightly thinner but with wider hit area */
.accordion-body pre::-webkit-scrollbar {
  width: 5px;
  height: 5px;
}

.accordion-body pre::-webkit-scrollbar-thumb {
  border-radius: 2px;
  border: 1px solid transparent;
}

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (max-width: 768px) {
  .hero-title {
    font-size: 2.25rem;
  }

  .section-title {
    font-size: 1.5rem;
  }

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

  .stats-row {
    grid-template-columns: 1fr 1fr;
  }

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

  .bookshelf {
    grid-template-columns: repeat(2, 1fr);
  }

  .site-section {
    padding: 3rem 0;
  }

  .site-section::after,
  .site-section::before {
    display: none;
  }
}

@media (max-width: 480px) {
  .hero-cta {
    flex-direction: column;
    align-items: center;
  }

  .btn-glass {
    width: 100%;
    max-width: 280px;
    justify-content: center;
  }

  .stats-row {
    grid-template-columns: 1fr;
  }
}

/* ============================================================
   SCROLL FADE-IN ANIMATION
   ============================================================ */
.fade-in-section {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.7s ease-out, transform 0.7s ease-out;
}

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

/* Staggered children animation */
.stagger-children > * {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.5s ease-out, transform 0.5s ease-out;
}

.stagger-children.visible > *:nth-child(1) { transition-delay: 0.05s; }
.stagger-children.visible > *:nth-child(2) { transition-delay: 0.10s; }
.stagger-children.visible > *:nth-child(3) { transition-delay: 0.15s; }
.stagger-children.visible > *:nth-child(4) { transition-delay: 0.20s; }
.stagger-children.visible > *:nth-child(5) { transition-delay: 0.25s; }
.stagger-children.visible > *:nth-child(6) { transition-delay: 0.30s; }
.stagger-children.visible > *:nth-child(7) { transition-delay: 0.35s; }
.stagger-children.visible > *:nth-child(8) { transition-delay: 0.40s; }

.stagger-children.visible > * {
  opacity: 1;
  transform: translateY(0);
}

/* ============================================================
   BACK TO TOP BUTTON
   ============================================================ */
.back-to-top {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 44px;
  height: 44px;
  border-radius: 12px;
  background: var(--surface-glass-strong);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--glass-border);
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: all 0.3s ease;
  z-index: 900;
  box-shadow: var(--glass-shadow);
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.back-to-top:hover {
  background: var(--accent-primary);
  color: white;
  border-color: var(--accent-primary);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px var(--accent-glow);
}

/* ============================================================
   ENHANCED HERO ORBS
   ============================================================ */
.hero-orb--1 {
  animation: orb-drift-1 24s ease-in-out infinite;
}

.hero-orb--2 {
  animation: orb-drift-2 20s ease-in-out infinite;
}

.hero-orb--3 {
  animation: orb-drift-3 28s ease-in-out infinite;
}

@keyframes orb-drift-1 {
  0%, 100% { transform: translate(0, 0) scale(1); }
  20% { transform: translate(40px, -50px) scale(1.08); }
  40% { transform: translate(-30px, 30px) scale(0.92); }
  60% { transform: translate(50px, 20px) scale(1.05); }
  80% { transform: translate(-20px, -40px) scale(0.97); }
}

@keyframes orb-drift-2 {
  0%, 100% { transform: translate(0, 0) scale(1); }
  25% { transform: translate(-50px, 40px) scale(1.1); }
  50% { transform: translate(30px, -30px) scale(0.9); }
  75% { transform: translate(-40px, -20px) scale(1.05); }
}

@keyframes orb-drift-3 {
  0%, 100% { transform: translate(0, 0) scale(1); }
  33% { transform: translate(60px, -30px) scale(1.12); }
  66% { transform: translate(-40px, 50px) scale(0.88); }
}

/* ============================================================
   ENHANCED NAV SCROLL STATE
   ============================================================ */
.site-nav.scrolled {
  background: var(--surface-glass-strong);
  backdrop-filter: blur(32px) saturate(180%);
  -webkit-backdrop-filter: blur(32px) saturate(180%);
  border-bottom: 1px solid var(--glass-border);
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.08);
}

[data-theme="dark"] .site-nav.scrolled {
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.3);
}

/* ============================================================
   STAT NUMBER COUNTER ANIMATION
   ============================================================ */
.stat-number {
  font-size: 2.5rem;
  font-weight: 800;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1.2;
  margin-bottom: 0.25rem;
  transition: transform 0.3s ease;
}

.stat-card:hover .stat-number {
  transform: scale(1.05);
}

/* ============================================================
   SKIP NAVIGATION (Accessibility)
   ============================================================ */
.skip-nav {
  position: absolute;
  top: -100%;
  left: 0;
  padding: 0.5rem 1rem;
  background: var(--accent-primary);
  color: #fff;
  z-index: 9999;
  border-radius: 0 0 4px 0;
  font-weight: 600;
  text-decoration: none;
}

.skip-nav:focus {
  top: 0;
}

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