@import url('https://fonts.googleapis.com/css2?family=Space+Mono:wght@400;700&family=Work+Sans:wght@400;600;800&display=swap');
@import url('https://fonts.googleapis.com/css2?family=Share+Tech+Mono&family=Rajdhani:wght@400;600;700&family=Inter:wght@300;400;500;600&display=swap');

  :root {
    --bg-deep: var(--bg-base);
    --bg-card: var(--bg-panel);
    --text-primary: var(--text-main);
    --text-secondary: var(--text-muted);
    --text-dim: var(--text-muted);
    --border: var(--border-color);
    --border-bright: var(--border-color);
    --grid-line: rgba(30,58,95,0.25);
    
    --bg-base: #f4f4f0;
    --bg-panel: #ffffff;
    --bg-chat: #ffffff;
    --accent-primary: #D9291C;
    --accent-glow: transparent;
    --text-main: #0a0a0a;
    --text-muted: #444444;
    --border-dim: #0a0a0a;
    --danger: #D9291C;
    --border-width: 4px;
    --bauhaus-blue: #005A9C;
    --bauhaus-yellow: #F2A900;
    --grid-dot: var(--grid-dot);
}

  *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

  html {
    min-height: 100%;
    background: var(--bg-deep, var(--bg-base, #111111));
  }

  body {
    zoom: 0.9;
    background: var(--bg-deep);
    color: var(--text-primary);
    font-family: var(--body);
    min-height: 111.111111vh; min-height: calc(100vh / 0.9);
    overflow-x: hidden;
  }

  /* ── TOP STICKY NAVIGATION BAR ── */
  .masterguide-nav {
    position: sticky;
    top: 0;
    z-index: 1000;
    background: var(--bg-panel);
    border-bottom: var(--border-width) solid var(--border-dim);
    padding: 12px 28px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 16px;
    box-shadow: 0 4px 0 rgba(0, 0, 0, 0.08);
  }

  .masterguide-nav .nav-brand {
    display: flex;
    align-items: center;
    gap: 12px;
    text-decoration: none;
    color: var(--text-primary);
    transition: transform 0.15s ease;
  }

  .masterguide-nav .nav-brand:hover {
    transform: translateY(-1px);
  }

  .masterguide-nav .brand-badge {
    background: var(--bauhaus-red, #D9291C);
    color: #ffffff;
    font-family: 'Space Mono', monospace;
    font-size: 1.25rem;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 2px solid var(--border-dim);
    box-shadow: 2px 2px 0 var(--border-dim);
    border-radius: 4px;
    flex-shrink: 0;
  }

  .masterguide-nav .brand-text {
    display: flex;
    flex-direction: column;
  }

  .masterguide-nav .brand-title {
    font-family: 'Space Mono', monospace;
    font-size: 1.05rem;
    font-weight: 700;
    letter-spacing: 0.5px;
    text-transform: uppercase;
    color: var(--text-primary);
    line-height: 1.2;
  }

  .masterguide-nav .brand-sub {
    font-size: 0.68rem;
    font-family: 'Space Mono', monospace;
    color: var(--text-dim);
    letter-spacing: 0.5px;
    margin-top: 2px;
  }

  .masterguide-nav .nav-actions {
    display: flex;
    align-items: center;
    gap: 12px;
    flex-wrap: wrap;
  }

  .masterguide-nav .nav-btn {
    font-family: 'Space Mono', monospace;
    font-weight: 700;
    font-size: 0.78rem;
    letter-spacing: 0.5px;
    padding: 8px 16px;
    cursor: pointer;
    text-transform: uppercase;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    border: 2px solid var(--border-dim);
    box-shadow: 3px 3px 0 var(--border-dim);
    transition: transform 0.12s ease, box-shadow 0.12s ease;
    user-select: none;
  }

  .masterguide-nav .nav-btn:hover {
    transform: translate(-1px, -1px);
    box-shadow: 4px 4px 0 var(--border-dim);
  }

  .masterguide-nav .nav-btn:active {
    transform: translate(1px, 1px);
    box-shadow: 1px 1px 0 var(--border-dim);
  }

  .masterguide-nav .btn-theme {
    background: var(--bg-panel);
    color: var(--text-primary);
  }

  .masterguide-nav .btn-lang {
    background: #e76f51;
    color: #ffffff;
  }

  .masterguide-nav .btn-roadmap {
    background: #2a9d8f;
    color: #ffffff;
  }

  .masterguide-nav .btn-quiz {
    background: #005A9C;
    color: #ffffff;
  }

  .masterguide-nav .btn-main {
    background: #D9291C;
    color: #ffffff;
  }

  .masterguide-nav .btn-icon {
    font-size: 1rem;
    line-height: 1;
  }

  .masterguide-nav .btn-back-label {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    line-height: 1;
  }

  .masterguide-nav .btn-back-sub {
    font-size: 0.55rem;
    opacity: 0.85;
    letter-spacing: 0.5px;
    line-height: 1;
    margin-bottom: 2px;
  }

  /* ── HERO ── */
  .hero {
    position: relative;
    padding: 80px 40px 60px;
    text-align: center;
    overflow: hidden;
    border-bottom: var(--border-width) solid var(--border-dim);
  }
  .hero::before {
    content: '';
    position: absolute; inset: 0;
    background: radial-gradient(ellipse 80% 60% at 50% 0%, rgba(59,130,246,0.18) 0%, transparent 70%);
    pointer-events: none;
  }
  .hero-grid {
    position: absolute; inset: 0;
    background-image: linear-gradient(var(--grid-line) 1px, transparent 1px),
                      linear-gradient(90deg, var(--grid-line) 1px, transparent 1px);
    background-size: 40px 40px;
    animation: gridPulse 8s ease-in-out infinite;
  }
  @keyframes gridPulse { 0%,100%{opacity:.4} 50%{opacity:.8} }

  .hero-badge {
    display: inline-block;
    font-family: var(--mono);
    font-size: 11px;
    color: var(--accent-cyan);
    border: var(--border-width) solid var(--border-dim);
    padding: 4px 14px;
    border-radius: 0;
    letter-spacing: 3px;
    margin-bottom: 24px;
    position: relative;
    text-transform: uppercase;
  }
  .hero h1 {
    font-family: var(--display);
    font-size: clamp(2.5rem, 6vw, 5rem);
    font-weight: 700;
    letter-spacing: -1px;
    line-height: 1;
    position: relative;
    background: linear-gradient(135deg, #e2e8f0 0%, #3b82f6 50%, #06b6d4 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 16px;
  }
  .hero-sub {
    font-size: 1rem;
    color: var(--text-secondary);
    position: relative;
    max-width: 600px;
    margin: 0 auto 40px;
  }
  .hero-stats {
    display: flex;
    justify-content: center;
    gap: 48px;
    position: relative;
    flex-wrap: wrap;
  }
  .hero-stat-item {
    text-align: center;
  }
  .hero-stat-num {
    font-family: var(--display);
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--accent-blue);
    line-height: 1;
  }
  .hero-stat-label {
    font-family: var(--mono);
    font-size: 10px;
    color: var(--text-dim);
    letter-spacing: 2px;
    text-transform: uppercase;
    margin-top: 4px;
  }

  /* ── NAV SIDEBAR ── */
  .layout {
    display: grid;
    grid-template-columns: 260px 1fr;
    min-height: calc(100vh - 300px);
  }
  .sidebar {
    position: sticky;
    top: 64px;
    height: calc(100vh / 0.9 - 64px);
    overflow-y: auto;
    background: var(--bg-panel);
    border-right: var(--border-width) solid var(--border-dim);
    padding: 24px 0;
    scrollbar-width: thin;
    scrollbar-color: var(--scrollbar-thumb, var(--accent-blue, #3b82f6)) var(--scrollbar-track, transparent);
  }
  .sidebar-title {
    font-family: var(--mono);
    font-size: 10px;
    letter-spacing: 3px;
    color: var(--text-dim);
    padding: 0 20px 12px;
    text-transform: uppercase;
  }
  .nav-section {
    margin-bottom: 8px;
  }
  .nav-chapter-group {
    margin-bottom: 4px;
    border-radius: 4px;
    transition: all 0.2s ease;
  }

  .nav-cat {
    font-family: var(--display);
    font-size: 11px;
    font-weight: 700;
    letter-spacing: 1.5px;
    text-transform: uppercase;
    color: var(--text-secondary);
    padding: 8px 14px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: space-between;
    border-radius: 4px;
    margin: 2px 8px;
    transition: all 0.2s ease;
    user-select: none;
    border: 1px solid transparent;
  }
  .nav-cat:hover {
    color: var(--text-primary);
    background: rgba(255, 255, 255, 0.05);
    border-color: rgba(255, 255, 255, 0.1);
  }
  .nav-chapter-group.expanded .nav-cat,
  .nav-cat.active-cat {
    color: var(--accent-blue, #60a5fa);
    background: rgba(59, 130, 246, 0.12);
    border-left: 3px solid var(--accent-blue, #3b82f6);
    border-color: rgba(59, 130, 246, 0.3);
  }
  .nav-cat-left {
    display: flex;
    align-items: center;
    gap: 8px;
    flex: 1;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
  }
  .nav-cat .dot {
    width: 6px; height: 6px;
    border-radius: 50%;
    flex-shrink: 0;
  }
  .nav-cat-badge {
    font-family: var(--mono);
    font-size: 9px;
    font-weight: 700;
    background: rgba(255, 255, 255, 0.08);
    color: var(--text-dim);
    padding: 1px 6px;
    border-radius: 10px;
    margin-left: 6px;
  }
  .nav-chapter-group.expanded .nav-cat-badge,
  .nav-cat.active-cat .nav-cat-badge {
    background: rgba(59, 130, 246, 0.25);
    color: #93c5fd;
  }

  .nav-term-links {
    display: none;
    padding: 2px 0 6px 6px;
  }
  .nav-chapter-group.expanded .nav-term-links {
    display: block;
  }

  .nav-link {
    display: block;
    font-size: 12px;
    color: var(--text-secondary);
    padding: 5px 12px 5px 24px;
    text-decoration: none;
    transition: all 0.15s ease;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    border-radius: 3px;
    margin: 1px 8px;
  }
  .nav-link:hover { color: var(--text-primary); background: rgba(59,130,246,0.08); }
  .nav-link.active { color: var(--accent-blue, #60a5fa); background: rgba(59, 130, 246, 0.15); font-weight: 700; }

  /* ── MAIN CONTENT & SINGLE CHAPTER AT A TIME ── */
  .main {
    padding: 40px;
    max-width: 960px;
  }

  .chapter {
    display: none;
    margin-bottom: 50px;
  }
  .chapter.active-chapter {
    display: block;
    animation: fadeInChapter 0.25s cubic-bezier(0.16, 1, 0.3, 1);
  }
  @keyframes fadeInChapter {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
  }

  /* ── CHAPTER BOTTOM PAGINATION BAR ── */
  .chapter-nav-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 16px;
    margin-top: 40px;
    margin-bottom: 20px;
    padding: 20px;
    background: var(--bg-card);
    border: var(--border-width) solid var(--border-dim);
    border-radius: 6px;
    box-shadow: 4px 4px 0 var(--border-dim);
    flex-wrap: wrap;
  }

  .chapter-nav-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: var(--bg-panel);
    color: var(--text-primary);
    border: 2px solid var(--border-dim);
    padding: 10px 18px;
    font-family: var(--display);
    font-size: 0.85rem;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.15s ease;
    box-shadow: 2px 2px 0 var(--border-dim);
  }

  .chapter-nav-btn:hover:not(:disabled) {
    transform: translate(-1px, -1px);
    box-shadow: 4px 4px 0 var(--border-dim);
    border-color: var(--accent-blue, #3b82f6);
    color: var(--accent-blue, #3b82f6);
  }

  .chapter-nav-btn:disabled {
    opacity: 0.35;
    cursor: not-allowed;
    box-shadow: none;
  }

  .chapter-indicator {
    font-family: var(--mono);
    font-size: 0.85rem;
    font-weight: 700;
    color: var(--accent-blue, #3b82f6);
    text-transform: uppercase;
    letter-spacing: 1.5px;
  }

  /* Target card glow when jumped from sidebar */
  .term-card.target-highlight {
    animation: targetGlow 1.4s ease-out;
  }

  @keyframes targetGlow {
    0% { box-shadow: 0 0 0 3px var(--accent-blue, #3b82f6), 0 0 24px rgba(59, 130, 246, 0.8); }
    100% { box-shadow: 4px 4px 0 var(--border-dim); }
  }
  .chapter-header {
    display: flex;
    align-items: center;
    gap: 16px;
    margin-bottom: 32px;
    padding-bottom: 20px;
    border-bottom: var(--border-width) solid var(--border-dim);
  }
  .chapter-icon {
    font-size: 2rem;
    width: 56px; height: 56px;
    border-radius: 0;
    display: flex; align-items: center; justify-content: center;
    flex-shrink: 0;
  }
  .chapter-title-block h2 {
    font-family: var(--display);
    font-size: 1.8rem;
    font-weight: 700;
    letter-spacing: -0.5px;
  }
  .chapter-title-block p {
    font-size: 13px;
    color: var(--text-secondary);
    margin-top: 4px;
  }

  /* ── TERM CARD ── */
  .term-card {
    background: var(--bg-card);
    border: var(--border-width) solid var(--border-dim);
    border-radius: 0;
    margin-bottom: 24px;
    overflow: hidden;
    transition: border-color 0.2s;
  }
  .term-card:hover { border-color: var(--border-bright); }

  .term-header {
    padding: 20px 24px;
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: 16px;
    cursor: pointer;
    user-select: none;
  }
  .term-header-left {
    display: flex;
    align-items: center;
    gap: 14px;
  }
  .term-icon {
    font-size: 1.4rem;
    width: 44px; height: 44px;
    border-radius: 0;
    display: flex; align-items: center; justify-content: center;
    flex-shrink: 0;
  }
  .term-name {
    font-family: var(--display);
    font-size: 1.25rem;
    font-weight: 700;
    letter-spacing: 0.3px;
  }
  .term-tagline {
    font-size: 12px;
    color: var(--text-secondary);
    margin-top: 3px;
    font-style: italic;
  }
  .term-badge {
    font-family: var(--mono);
    font-size: 9px;
    letter-spacing: 2px;
    padding: 3px 10px;
    border-radius: 0;
    border: 1px solid;
    white-space: nowrap;
    flex-shrink: 0;
    text-transform: uppercase;
  }
  .expand-btn {
    font-size: 18px;
    color: var(--text-dim);
    flex-shrink: 0;
    transition: transform 0.3s;
  }
  .term-card.open .expand-btn { transform: rotate(180deg); }

  .term-body {
    display: none;
    padding: 0 24px 24px;
    border-top: var(--border-width) solid var(--border-dim);
  }
  .term-card.open .term-body { display: block; }

  /* ── CONTENT BLOCKS ── */
  .content-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
    margin-top: 20px;
  }
  @media(max-width:700px){ .content-grid{ grid-template-columns:1fr; } }

  .block {
    background: var(--bg-panel);
    border: var(--border-width) solid var(--border-dim);
    border-radius: 0;
    padding: 16px;
  }
  .block-label {
    font-family: var(--mono);
    font-size: 9px;
    letter-spacing: 2px;
    color: var(--text-dim);
    text-transform: uppercase;
    margin-bottom: 10px;
    display: flex;
    align-items: center;
    gap: 6px;
  }
  .block-label::after {
    content: '';
    flex: 1;
    height: 1px;
    background: var(--border);
  }
  .block p {
    font-size: 13.5px;
    color: var(--text-secondary);
    line-height: 1.7;
  }
  .block.full { grid-column: 1/-1; }

  .how-it-works {
    margin-top: 20px;
  }
  .step-list {
    counter-reset: steps;
    list-style: none;
    margin-top: 12px;
  }
  .step-list li {
    counter-increment: steps;
    display: flex;
    gap: 12px;
    margin-bottom: 10px;
    font-size: 13px;
    color: var(--text-secondary);
    line-height: 1.6;
  }
  .step-list li::before {
    content: counter(steps);
    font-family: var(--mono);
    font-size: 11px;
    color: var(--accent-cyan);
    background: rgba(6,182,212,0.1);
    border: var(--border-width) solid var(--border-dim);
    width: 22px; height: 22px;
    border-radius: 50%;
    display: flex; align-items: center; justify-content: center;
    flex-shrink: 0;
    margin-top: 1px;
  }

  /* ── ATTACK FLOW DIAGRAM ── */
  .flow-diagram {
    margin-top: 20px;
    background: var(--bg-panel);
    border: var(--border-width) solid var(--border-dim);
    border-radius: 0;
    padding: 20px;
    overflow-x: auto;
  }
  .flow-label {
    font-family: var(--mono);
    font-size: 9px;
    letter-spacing: 2px;
    color: var(--text-dim);
    margin-bottom: 16px;
    text-transform: uppercase;
  }
  .flow-nodes {
    display: flex;
    align-items: center;
    gap: 0;
    flex-wrap: nowrap;
    overflow-x: auto;
    padding-bottom: 8px;
  }
  .flow-node {
    flex-shrink: 0;
    background: var(--bg-card);
    border: var(--border-width) solid var(--border-dim);
    border-radius: 0;
    padding: 10px 14px;
    text-align: center;
    min-width: 90px;
  }
  .flow-node-icon { font-size: 1.2rem; }
  .flow-node-text { font-size: 11px; color: var(--text-secondary); margin-top: 4px; line-height: 1.3; }
  .flow-arrow {
    color: var(--accent-blue);
    font-size: 18px;
    padding: 0 6px;
    flex-shrink: 0;
  }
  .flow-node.attacker { border-color: var(--accent-red); }
  .flow-node.victim { border-color: var(--accent-green); }
  .flow-node.server { border-color: var(--accent-orange); }
  .flow-node.middle { border-color: var(--accent-purple); }

  /* ── SEVERITY BAR ── */
  .severity-row {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-top: 16px;
    flex-wrap: wrap;
  }
  .sev-label { font-size: 12px; color: var(--text-dim); font-family: var(--mono); }
  .sev-bar-wrap {
    flex: 1;
    height: 6px;
    background: rgba(255,255,255,0.06);
    border-radius: 0;
    min-width: 100px;
  }
  .sev-bar { height: 100%; border-radius: 0; }
  .sev-tag {
    font-size: 11px;
    font-family: var(--mono);
    padding: 2px 10px;
    border-radius: 0;
  }
  .crit { background: rgba(239,68,68,0.15); color: var(--accent-red); border: var(--border-width) solid var(--border-dim); }
  .high { background: rgba(249,115,22,0.15); color: var(--accent-orange); border: var(--border-width) solid var(--border-dim); }
  .med { background: rgba(234,179,8,0.15); color: var(--accent-yellow); border: var(--border-width) solid var(--border-dim); }
  .low { background: rgba(16,185,129,0.15); color: var(--accent-green); border: var(--border-width) solid var(--border-dim); }

  /* ── CODE BLOCK ── */
  .code-block {
    background: #020b18;
    border: var(--border-width) solid var(--border-dim);
    border-radius: 0;
    padding: 14px 16px;
    margin-top: 12px;
    font-family: var(--mono);
    font-size: 12px;
    color: #7dd3fc;
    overflow-x: auto;
    white-space: pre;
    line-height: 1.7;
  }
  .code-block .comment { color: var(--text-dim); }
  .code-block .keyword { color: #a78bfa; }
  .code-block .string { color: #86efac; }
  .code-block .bad { color: var(--accent-red); }

  /* ── REAL LIFE EXAMPLE ── */
  .real-example {
    background: rgba(16,185,129,0.05);
    border-left: 3px solid var(--accent-green);
    border-radius: 0 8px 8px 0;
    padding: 14px 16px;
    margin-top: 16px;
  }
  .real-example-label {
    font-family: var(--mono);
    font-size: 9px;
    letter-spacing: 2px;
    color: var(--accent-green);
    margin-bottom: 8px;
    text-transform: uppercase;
  }
  .real-example p { font-size: 13px; color: var(--text-secondary); line-height: 1.7; }

  .defense-box {
    background: rgba(59,130,246,0.05);
    border-left: 3px solid var(--accent-blue);
    border-radius: 0 8px 8px 0;
    padding: 14px 16px;
    margin-top: 12px;
  }
  .defense-label {
    font-family: var(--mono);
    font-size: 9px;
    letter-spacing: 2px;
    color: var(--accent-blue);
    margin-bottom: 8px;
    text-transform: uppercase;
  }
  .defense-box ul { list-style: none; }
  .defense-box li {
    font-size: 13px;
    color: var(--text-secondary);
    padding: 4px 0;
    display: flex;
    gap: 8px;
  }
  .defense-box li::before { content: '→'; color: var(--accent-blue); flex-shrink: 0; }

  /* ── CHAPTER COLOR THEMES ── */
  .ch-red .chapter-icon { background: rgba(239,68,68,0.1); }
  .ch-orange .chapter-icon { background: rgba(249,115,22,0.1); }
  .ch-blue .chapter-icon { background: var(--bauhaus-blue); }
  .ch-cyan .chapter-icon { background: rgba(6,182,212,0.1); }
  .ch-purple .chapter-icon { background: rgba(168,85,247,0.1); }
  .ch-green .chapter-icon { background: var(--bauhaus-yellow); }
  .ch-yellow .chapter-icon { background: rgba(234,179,8,0.1); }
  .ch-pink .chapter-icon { background: rgba(236,72,153,0.1); }
  .ch-indigo .chapter-icon { background: rgba(99,102,241,0.1); }
  .ch-teal .chapter-icon { background: rgba(20,184,166,0.1); }

  .badge-threat { color: var(--accent-red); border-color: rgba(239,68,68,0.4); background: rgba(239,68,68,0.07); }
  .badge-malware { color: var(--accent-orange); border-color: rgba(249,115,22,0.4); background: rgba(249,115,22,0.07); }
  .badge-defense { color: var(--accent-green); border-color: rgba(16,185,129,0.4); background: rgba(16,185,129,0.07); }
  .badge-crypto { color: var(--accent-blue); border-color: rgba(59,130,246,0.4); background: rgba(59,130,246,0.07); }
  .badge-iam { color: var(--accent-cyan); border-color: rgba(6,182,212,0.4); background: rgba(6,182,212,0.07); }
  .badge-network { color: var(--accent-purple); border-color: rgba(168,85,247,0.4); background: rgba(168,85,247,0.07); }
  .badge-adv { color: var(--accent-pink); border-color: rgba(236,72,153,0.4); background: rgba(236,72,153,0.07); }
  .badge-gov { color: var(--accent-yellow); border-color: rgba(234,179,8,0.4); background: rgba(234,179,8,0.07); }
  .badge-ops { color: #818cf8; border-color: rgba(129,140,248,0.4); background: rgba(129,140,248,0.07); }
  .badge-emerging { color: #2dd4bf; border-color: rgba(45,212,191,0.4); background: rgba(45,212,191,0.07); }

  /* ── SCROLLBAR ── */
  * {
    scrollbar-width: thin;
    scrollbar-color: var(--scrollbar-thumb, var(--accent-blue, #3b82f6)) var(--scrollbar-track, transparent);
  }
  ::-webkit-scrollbar { width: 7px; height: 7px; }
  ::-webkit-scrollbar-track { background: var(--scrollbar-track, transparent); }
  ::-webkit-scrollbar-thumb { 
    background: var(--scrollbar-thumb, var(--accent-blue, #3b82f6)); 
    border-radius: 3px; 
    border: 1px solid var(--scrollbar-border, rgba(255, 255, 255, 0.12));
    transition: background 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
  }
  ::-webkit-scrollbar-thumb:hover { 
    background: var(--scrollbar-thumb-hover, #60a5fa); 
    box-shadow: 0 0 8px var(--scrollbar-glow, rgba(59, 130, 246, 0.6));
  }
  ::-webkit-scrollbar-corner { background: var(--scrollbar-track, transparent); }

  /* ── SEARCH ── */
  .search-bar {
    padding: 16px 20px;
    border-bottom: var(--border-width) solid var(--border-dim);
  }
  .search-input {
    width: 100%;
    background: var(--bg-card);
    border: var(--border-width) solid var(--border-dim);
    border-radius: 0;
    padding: 8px 12px;
    color: var(--text-primary);
    font-family: var(--mono);
    font-size: 12px;
    outline: none;
    transition: border-color 0.2s;
  }
  .search-input:focus { border-color: var(--accent-blue); }
  .search-input::placeholder { color: var(--text-dim); }

  .back-to-top {
    position: fixed;
    bottom: 32px;
    right: 32px;
    background: var(--accent-blue);
    color: white;
    border: none;
    border-radius: 50%;
    width: 44px; height: 44px;
    font-size: 18px;
    cursor: pointer;
    display: flex; align-items: center; justify-content: center;
    opacity: 0;
    transition: opacity 0.3s;
    z-index: 99;
  }
  .back-to-top.show { opacity: 1; }

  .tag-row {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
    margin-top: 14px;
  }
  .tag {
    font-family: var(--mono);
    font-size: 10px;
    padding: 3px 10px;
    border-radius: 0;
    background: rgba(255,255,255,0.04);
    border: var(--border-width) solid var(--border-dim);
    color: var(--text-dim);
  }

  .analogy-box {
    background: rgba(234,179,8,0.05);
    border-left: 3px solid var(--accent-yellow);
    border-radius: 0 8px 8px 0;
    padding: 14px 16px;
    margin-top: 12px;
  }
  .analogy-label {
    font-family: var(--mono);
    font-size: 9px;
    letter-spacing: 2px;
    color: var(--accent-yellow);
    margin-bottom: 8px;
    text-transform: uppercase;
  }
  .analogy-box p { font-size: 13px; color: var(--text-secondary); line-height: 1.7; }

  @media(max-width:768px){
    html { font-size: 14px; }
    .layout{grid-template-columns:1fr;}
    .hero{padding:24px 14px 20px;}
    .hero h1{font-size:2rem;letter-spacing:-0.5px;}
    .hero p{font-size:0.85rem;}
    .hero-stats{gap:10px;margin-top:14px;flex-wrap:wrap;}
    .hero-stat-item{padding:5px 10px;}
    .hero-stat-num{font-size:1.4rem;}
    
    /* Sleek scrollable sidebar index so 100 links never push chapter content down */
    .sidebar{
      position:relative;
      height:auto;
      max-height:220px;
      overflow-y:auto;
      border-right:none;
      border-bottom:var(--border-width) solid var(--border-dim);
      padding:10px 14px;
      scrollbar-width:thin;
    }
    .masterguide-nav {
      padding: 10px 14px;
      flex-wrap: wrap;
      gap: 10px;
    }
    .masterguide-nav .brand-title {
      font-size: 0.88rem;
    }
    .masterguide-nav .brand-sub {
      display: none;
    }
    .masterguide-nav .nav-actions {
      width: 100%;
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 6px;
    }
    .masterguide-nav .nav-btn {
      font-size: 0.65rem;
      padding: 6px 4px;
      justify-content: center;
      gap: 4px;
      text-align: center;
    }
    .search-bar { padding: 10px 14px; }
    .search-input { padding: 8px 12px; font-size: 0.82rem; }

    .main{padding:14px 10px;}
    .chapter{margin-bottom:35px;}
    .chapter-header{gap:10px;margin-bottom:14px;}
    .chapter-icon{width:36px;height:36px;font-size:18px;}
    .chapter-title-block h2{font-size:1.35rem;}
    .chapter-title-block p{font-size:0.82rem;}
    .term-card{margin-bottom:12px;border-width:2px;box-shadow:3px 3px 0 var(--border-dim);}
    .term-header{padding:10px 12px;}
    .term-name{font-size:0.98rem;}
    .term-tagline{font-size:0.75rem;}
    .term-body{padding:12px 10px;}
    .content-grid{grid-template-columns:1fr;gap:8px;}
    .block{padding:10px;}
  }
[data-theme="dark"] {
    --bg-base: #111111;
    --bg-panel: #1a1a1a;
    --bg-chat: #1a1a1a;
    --text-main: #f4f4f0;
    --text-muted: #aaaaaa;
    --border-dim: #f4f4f0;
    --border-color: #f4f4f0;
    --grid-dot: #333333;
    --grid-line: rgba(255,255,255,0.1);
}

.profile-container .theme-btn {
    background: var(--text-main);
    color: var(--bg-base);
}

.theme-btn-floating {
    position: fixed;
    bottom: 20px;
    left: 20px;
    background: var(--text-main);
    color: var(--bg-base);
    border: var(--border-width) solid var(--border-dim);
    font-family: 'Space Mono', monospace;
    font-weight: 700;
    font-size: 0.85rem;
    padding: 10px 15px;
    cursor: pointer;
    text-transform: uppercase;
    box-shadow: 4px 4px 0 var(--border-dim);
    transition: all 0.1s;
    z-index: 9999;
}
.theme-btn-floating:hover {
    transform: translate(2px, 2px);
    box-shadow: 2px 2px 0 var(--border-dim);
}