:root {
    --bg: #191127;
    --surface: #23133a;
    --border: #3a1c63;
    --accent: #883CF0;
    --accent2: #7c3aed;
    --accent3: #8b5cf6;
    --text: #e8eaf0;
    --muted: #d6d6d6;
    --code-bg: #0f0818;
    --green: #00e5a0;
    --amber: #ffb347;
    --red: #ff5f5f;
  }

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

  html { scroll-behavior: smooth; }

  body {
    background: var(--bg);
    color: var(--text);
    font-family: 'DM Sans', sans-serif;
    font-size: 16px;
    line-height: 1.6;
    overflow-x: hidden;
  }

  /* NOISE OVERLAY */
  body::before {
    content: '';
    position: fixed; inset: 0;
    background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)' opacity='0.04'/%3E%3C/svg%3E");
    pointer-events: none;
    z-index: 9999;
    opacity: 0.35;
  }

  /* ── NAV ── */
  nav {
    position: fixed; top: 0; left: 0; right: 0;
    z-index: 100;
    display: flex; align-items: center; justify-content: space-between;
    padding: 18px 48px;
    background: #180f26;
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
  }
  .logo {
    font-family: 'Syne', sans-serif;
    font-weight: 800;
    font-size: 1.15rem;
    letter-spacing: -0.02em;
    display: flex; align-items: center; gap: 10px;
  }
  .logo-dot { width: 8px; height: 8px; border-radius: 50%; background: var(--accent); animation: pulse 2s infinite; }
  @keyframes pulse { 0%,100%{box-shadow:0 0 0 0 rgba(134, 0, 229, 0.4)} 50%{box-shadow:0 0 0 8px rgba(126, 0, 229, 0)} }

  .nav-links { display: flex; gap: 32px; }
  .nav-links a {
    color: var(--muted);
    text-decoration: none;
    font-size: 0.88rem;
    font-family: 'JetBrains Mono', monospace;
    transition: color 0.2s;
  }
  .nav-links a:hover { color: var(--accent); }

  /* ── HERO ── */
  .hero {
    min-height: 100vh;
    display: flex; align-items: center;
    padding: 120px 48px 80px;
    position: relative;
    overflow: hidden;
  }

  .hero-grid {
    position: absolute; inset: 0;
    background-image:
      linear-gradient(rgba(0,229,160,0.03) 1px, transparent 1px),
      linear-gradient(90deg, rgba(0,229,160,0.03) 1px, transparent 1px);
    background-size: 60px 60px;
  }

  .hero-glow {
    position: absolute;
    width: 600px; height: 600px;
    border-radius: 50%;
    background: radial-gradient(circle, rgba(141, 0, 229, 0.08) 0%, transparent 70%);
    top: -100px; right: -100px;
    pointer-events: none;
  }
  .hero-glow2 {
    position: absolute;
    width: 400px; height: 400px;
    border-radius: 50%;
    background: radial-gradient(circle, rgba(187, 91, 255, 0.06) 0%, transparent 70%);
    bottom: -80px; left: 200px;
    pointer-events: none;
  }

  .hero-content { max-width: 760px; position: relative; z-index: 1; }

  .hero-badge {
    display: inline-flex; align-items: center; gap: 8px;
    background: #1f1232;
    border: 1px solid #3a1c63;
    color: var(--accent);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.75rem;
    padding: 6px 14px;
    border-radius: 4px;
    margin-bottom: 32px;
    animation: fadeUp 0.6s ease both;
  }

  h1 {
    font-family: 'Syne', sans-serif;
    font-weight: 800;
    font-size: clamp(2.8rem, 6vw, 4.8rem);
    line-height: 1.02;
    letter-spacing: -0.03em;
    margin-bottom: 24px;
    animation: fadeUp 0.6s ease 0.1s both;
  }
  h1 span { color: var(--accent); }

  .hero-sub {
    font-size: 1.15rem;
    color: #cad0d8;
    max-width: 520px;
    line-height: 1.7;
    margin-bottom: 48px;
    font-weight: 300;
    animation: fadeUp 0.6s ease 0.2s both;
  }

  .hero-actions {
    display: flex; gap: 16px; flex-wrap: wrap;
    animation: fadeUp 0.6s ease 0.3s both;
  }

  .btn-primary {
    background: var(--accent);
    color: #000;
    font-family: 'Syne', sans-serif;
    font-weight: 700;
    font-size: 0.9rem;
    padding: 14px 28px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    text-decoration: none;
    transition: transform 0.15s, box-shadow 0.15s;
    display: inline-flex; align-items: center; gap: 8px;
  }
  .btn-primary:hover { transform: translateY(-2px); box-shadow: 0 8px 30px rgba(145, 0, 229, 0.3); }

  .btn-ghost {
    background: transparent;
    color: var(--text);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    padding: 14px 28px;
    border: 1px solid var(--border);
    border-radius: 4px;
    cursor: pointer;
    text-decoration: none;
    transition: border-color 0.2s, color 0.2s;
    display: inline-flex; align-items: center; gap: 8px;
  }
  .btn-ghost:hover { border-color: var(--accent); color: var(--accent); }

  /* ── STATS BAR ── */
  .stats-bar {
    background: var(--surface);
    border-top: 1px solid var(--border);
    border-bottom: 1px solid var(--border);
    padding: 24px 48px;
    display: flex; gap: 48px; flex-wrap: wrap;
  }
  .stat { display: flex; flex-direction: column; gap: 2px; }
  .stat-num {
    font-family: 'Syne', sans-serif;
    font-weight: 800;
    font-size: 1.8rem;
    color: var(--accent);
    line-height: 1;
  }
  .stat-label { font-size: 0.8rem; color: var(--muted); font-family: 'JetBrains Mono', monospace; }

  /* ── SECTION ── */
  section { padding: 80px 48px; }
  .section-label {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.72rem;
    color: var(--accent);
    letter-spacing: 0.15em;
    text-transform: uppercase;
    margin-bottom: 12px;
  }
  h2 {
    font-family: 'Syne', sans-serif;
    font-weight: 800;
    font-size: clamp(1.8rem, 3vw, 2.8rem);
    letter-spacing: -0.02em;
    line-height: 1.1;
    margin-bottom: 16px;
  }
  .section-desc { color: #c0c9d6; font-size: 1rem; max-width: 540px; font-weight: 300; }

  /* ── OS SELECTOR ── */
  #setup { background: var(--surface); border-top: 1px solid var(--border); }

  .os-tabs {
    display: flex; gap: 0;
    background: var(--code-bg);
    border: 1px solid var(--border);
    border-radius: 6px;
    overflow: hidden;
    width: fit-content;
    margin: 32px 0;
  }
  .os-tab {
    padding: 12px 28px;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.82rem;
    color: var(--muted);
    cursor: pointer;
    border: none;
    background: transparent;
    transition: all 0.2s;
    display: flex; align-items: center; gap: 8px;
    border-right: 1px solid var(--border);
  }
  .os-tab:last-child { border-right: none; }
  .os-tab.active { background: var(--accent); color: #000; font-weight: 700; }
  .os-tab:hover:not(.active) { color: var(--text); background: #23133a9f; }

  .os-panel { display: none; }
  .os-panel.active { display: block; }

  /* ── STEPS ── */
  .steps { display: flex; flex-direction: column; gap: 0; margin-top: 8px; }

  .step {
    display: grid; grid-template-columns: 56px 1fr;
    gap: 0;
    position: relative;
  }
  .step:not(:last-child)::after {
    content: '';
    position: absolute;
    left: 27px; top: 56px;
    width: 2px;
    height: calc(100% - 40px);
    background: linear-gradient(to bottom, var(--border), transparent);
  }

  .step-num {
    width: 40px; height: 40px;
    border-radius: 50%;
    background: var(--code-bg);
    border: 2px solid var(--border);
    display: flex; align-items: center; justify-content: center;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.8rem;
    font-weight: 700;
    color: var(--muted);
    flex-shrink: 0;
    margin-top: 4px;
    transition: all 0.3s;
    cursor: pointer;
  }
  .step.done .step-num {
    background: var(--accent);
    border-color: var(--accent);
    color: #000;
  }
  .step.active .step-num {
    border-color: var(--accent);
    color: var(--accent);
    box-shadow: 0 0 0 4px rgba(0,229,160,0.1);
  }

  .step-content { padding: 4px 0 40px 20px; }
  .step-title {
    font-family: 'Syne', sans-serif;
    font-weight: 700;
    font-size: 1.1rem;
    margin-bottom: 8px;
    cursor: pointer;
    display: flex; align-items: center; gap: 10px;
  }
  .step-desc { color: #8090a8; font-size: 0.9rem; margin-bottom: 16px; font-weight: 300; }

  /* ── CODE BLOCK ── */
  .code-block {
    background: var(--code-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    overflow: hidden;
    margin: 12px 0;
    position: relative;
  }
  .code-header {
    display: flex; align-items: center; justify-content: space-between;
    padding: 10px 16px;
    border-bottom: 1px solid var(--border);
    background: rgba(255,255,255,0.02);
  }
  .code-lang {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.7rem;
    color: var(--muted);
    letter-spacing: 0.1em;
    text-transform: uppercase;
  }
  .copy-btn {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.7rem;
    color: var(--muted);
    background: transparent;
    border: 1px solid var(--border);
    padding: 4px 10px;
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.2s;
    display: flex; align-items: center; gap: 5px;
  }
  .copy-btn:hover { border-color: var(--accent); color: var(--accent); }
  .copy-btn.copied { color: var(--accent); border-color: var(--accent); }

  code {
    display: block;
    padding: 16px 20px;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    line-height: 1.7;
    color: #c9d1e0;
    overflow-x: auto;
    white-space: pre;
  }
  .cmd { color: var(--accent); }
  .comment { color: var(--muted); }
  .kw { color: var(--accent3); }
  .str { color: var(--amber); }
  .num { color: var(--accent2); }

  .step-done-btn {
    display: inline-flex; align-items: center; gap: 6px;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.78rem;
    color: var(--muted);
    background: transparent;
    border: 1px dashed var(--border);
    padding: 6px 14px;
    border-radius: 4px;
    cursor: pointer;
    margin-top: 8px;
    transition: all 0.2s;
  }
  .step-done-btn:hover { border-color: var(--accent); color: var(--accent); }

  /* ── PROGRESS ── */
  .progress-wrap {
    display: flex; align-items: center; gap: 16px;
    background: var(--code-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 16px 24px;
    margin-bottom: 32px;
  }
  .progress-label { font-family: 'JetBrains Mono', monospace; font-size: 0.8rem; color: var(--muted); white-space: nowrap; }
  .progress-bar-bg { flex: 1; height: 4px; background: var(--border); border-radius: 2px; overflow: hidden; }
  .progress-bar-fill { height: 100%; background: var(--accent); border-radius: 2px; transition: width 0.4s ease; width: 0%; }
  .progress-pct { font-family: 'JetBrains Mono', monospace; font-size: 0.8rem; color: var(--accent); min-width: 36px; text-align: right; }

  /* ── TERMINAL ── */
  #terminal-section { background: var(--bg); }
  .terminal {
    background: #0f0818;
    border: 1px solid var(--border);
    border-radius: 10px;
    overflow: hidden;
    max-width: 720px;
    box-shadow: 0 32px 80px rgba(0, 0, 0, 0.6), 0 0 0 1px rgba(255, 255, 255, 0.04);
    margin: 32px 0;
  }
  .terminal-bar {
    background: #2a1647;
    padding: 12px 16px;
    display: flex; align-items: center; gap: 8px;
    border-bottom: 1px solid var(--border);
  }
  .t-dot { width: 12px; height: 12px; border-radius: 50%; }
  .t-red { background: #ff5f56; }
  .t-yellow { background: #ffbd2e; }
  .t-green { background: #27c93f; }
  .terminal-title { font-family: 'JetBrains Mono', monospace; font-size: 0.72rem; color: var(--muted); margin-left: 8px; }

  .terminal-body { padding: 20px 24px; min-height: 260px; }
  .t-line { font-family: 'JetBrains Mono', monospace; font-size: 0.82rem; line-height: 1.8; }
  .t-prompt { color: var(--accent); }
  .t-output { color: #6b7789; }
  .t-success { color: var(--accent); }
  .t-warning { color: var(--amber); }
  .t-error { color: var(--red); }
  .t-cursor { display: inline-block; width: 8px; height: 14px; background: var(--accent); vertical-align: middle; animation: blink 1s step-end infinite; }
  @keyframes blink { 0%,100%{opacity:1} 50%{opacity:0} }

  .terminal-input-row {
    display: flex; align-items: center; gap: 8px;
    padding: 12px 24px;
    border-top: 1px solid var(--border);
    background: #050709;
  }
  .terminal-input-row span { font-family: 'JetBrains Mono', monospace; font-size: 0.82rem; color: var(--accent); }
  #term-input {
    flex: 1;
    background: transparent;
    border: none;
    outline: none;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.82rem;
    color: var(--text);
    caret-color: var(--accent);
  }

  /* ── CONCEPTS ── */
  #concepts { background: var(--surface); border-top: 1px solid var(--border); }
  .concepts-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 1px;
    background: var(--border);
    border: 1px solid var(--border);
    border-radius: 8px;
    overflow: hidden;
    margin-top: 40px;
  }
  .concept-card {
    background: var(--surface);
    padding: 28px;
    transition: background 0.2s;
    cursor: default;
  }
  .concept-card:hover { background: rgba(0,229,160,0.03); }
  .concept-icon {
    font-size: 1.5rem;
    margin-bottom: 16px;
    display: block;
  }
  .concept-title {
    font-family: 'Syne', sans-serif;
    font-weight: 700;
    font-size: 1rem;
    margin-bottom: 8px;
  }
  .concept-desc { font-size: 0.86rem; color: #8090a8; line-height: 1.6; font-weight: 300; }

  /* ── NPM CHEATSHEET ── */
  #npm { background: var(--bg); border-top: 1px solid var(--border); }
  .npm-table {
    width: 100%; max-width: 720px;
    border-collapse: collapse;
    margin-top: 32px;
  }
  .npm-table th {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.72rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--muted);
    padding: 12px 16px;
    text-align: left;
    border-bottom: 1px solid var(--border);
  }
  .npm-table td {
    padding: 14px 16px;
    border-bottom: 1px solid #3a1c63;
    font-size: 0.9rem;
  }
  .npm-table td:first-child {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.8rem;
    color: var(--accent);
    white-space: nowrap;
  }
  .npm-table td:last-child { color: #8090a8; font-weight: 300; }
  .npm-table tr:hover td { background: #23133a; }

  /* ── FOOTER ── */
  footer {
    background: var(--surface);
    border-top: 1px solid var(--border);
    padding: 40px 48px;
    display: flex; justify-content: space-between; align-items: center;
    flex-wrap: wrap; gap: 16px;
  }
  .footer-logo {
    font-family: 'Syne', sans-serif; font-weight: 800; font-size: 1rem;
    display: flex; align-items: center; gap: 8px;
  }
  .footer-note { font-size: 0.82rem; color: var(--muted); font-family: 'JetBrains Mono', monospace; }

  /* ── ANIMATIONS ── */
  @keyframes fadeUp {
    from { opacity: 0; transform: translateY(16px); }
    to { opacity: 1; transform: translateY(0); }
  }
  .fade-in { animation: fadeUp 0.5s ease both; }

  @media (max-width: 768px) {
    nav { padding: 14px 20px; }
    .nav-links { display: none; }
    .hero, section { padding: 80px 20px 60px; }
    .stats-bar { padding: 20px; gap: 24px; }
    footer { padding: 32px 20px; }
  }

  /* ── TOOLTIP ── */
  .tooltip-wrap { position: relative; display: inline-block; }
  .tooltip-box {
    position: absolute; bottom: 125%; left: 50%; transform: translateX(-50%);
    background: #1a1d27; border: 1px solid var(--border);
    padding: 6px 12px; border-radius: 4px;
    font-family: 'JetBrains Mono', monospace; font-size: 0.72rem; color: var(--text);
    white-space: nowrap; pointer-events: none; opacity: 0; transition: opacity 0.15s;
  }
  .tooltip-wrap:hover .tooltip-box { opacity: 1; }

  /* ── VERSION BADGE ── */
  .version-row { display: flex; gap: 12px; flex-wrap: wrap; margin: 20px 0; }
  .version-badge {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.78rem;
    padding: 6px 14px;
    border-radius: 4px;
    border: 1px solid;
    cursor: pointer;
    transition: all 0.2s;
  }
  .v-lts { color: var(--accent); border-color: #3a1c63; background: rgba(134, 0, 229, 0.06); }
  .v-lts:hover { background: #1f1232; }
  .v-current { color: var(--accent3); border-color: #5e309d; background: rgba(184, 91, 255, 0.06); }
  .v-current:hover { background: rgba(192, 91, 255, 0.12); }

  /* scroll indicator */
  .scroll-ind {
    position: absolute; bottom: 32px; left: 48px;
    display: flex; flex-direction: column; align-items: center; gap: 8px;
    color: var(--muted); font-family: 'JetBrains Mono', monospace; font-size: 0.7rem;
    letter-spacing: 0.1em; text-transform: uppercase;
    animation: fadeUp 1s ease 0.8s both;
  }
  .scroll-line { width: 1px; height: 40px; background: linear-gradient(to bottom, var(--muted), transparent); }