:root {
    --bg: #F4F4F6;
    --paper: #FFFFFF;
    --ink: #1A1A1A;
    --muted: #555555;
    --charcoal: #1A1A1A;
    --charcoal-2: #2D2D33;
    --accent: #0066FF;
    --accent-soft: #4D8FFF;
    --accent-dark: #0048B8;
    --cta: #FFD814;
    --link: #0066FF;
    --code-bg: #1E1E1E;
    --code-text: #E8E8E8;
    --tip-bg: #F0F6FF;
    --warn-bg: #FFE8E0;
  }

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

  html { scroll-behavior: smooth; scroll-padding-top: 80px; }

  body {
    font-family: 'Inter', -apple-system, sans-serif;
    background: var(--bg);
    color: var(--ink);
    line-height: 1.6;
    font-size: 16px;
  }

  /* ===== SCROLL PROGRESS BAR ===== */
  .progress {
    position: fixed;
    top: 0; left: 0;
    height: 4px;
    background: var(--accent);
    z-index: 1000;
    width: 0%;
    transition: width 0.1s;
  }

  /* ===== HEADER ===== */
  header.top {
    background: var(--paper);
    border-bottom: 3px solid var(--ink);
    padding: 24px 32px;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: 0 2px 0 var(--ink);
  }
  .top-inner {
    max-width: 1100px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 16px;
  }
  .brand {
    font-family: 'Syne', sans-serif;
    font-weight: 800;
    font-size: 24px;
    letter-spacing: -0.03em;
    color: var(--ink);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 8px;
  }
  .brand span { color: var(--accent); }
  .brand-mark {
    width: 28px;
    height: 28px;
    background: var(--accent);
    display: inline-block;
    transform: rotate(45deg);
    position: relative;
  }
  .brand-mark::after {
    content: '';
    position: absolute;
    inset: 6px;
    background: var(--paper);
    transform: rotate(45deg);
  }
  .top-meta {
    font-family: 'JetBrains Mono', monospace;
    font-size: 12px;
    color: var(--muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
  }

  .back-nav {
    font-family: 'JetBrains Mono', monospace;
    font-size: 13px;
    color: white;
    text-decoration: none;
    background: #E8621A;
    border: 2px solid var(--accent);
    padding: 6px 14px;
    transition: background 0.15s, box-shadow 0.15s;
  }
  .back-nav:hover {
    background: #D0531A;
    box-shadow: 0 0 0 3px #4D8FFF;
    color: white;
  }

  .view-sample-btn {
    font-family: 'JetBrains Mono', monospace;
    font-size: 13px;
    font-weight: 700;
    background: #2A9A5B;
    color: var(--paper);
    text-decoration: none;
    padding: 8px 18px;
    border: 2px solid var(--ink);
    box-shadow: 3px 3px 0 var(--ink);
    letter-spacing: 0.05em;
    text-transform: uppercase;
    transition: box-shadow 0.1s, transform 0.1s;
  }
  .view-sample-btn:hover {
    box-shadow: 1px 1px 0 var(--ink);
    transform: translate(2px, 2px);
  }

  /* ===== HERO ===== */
  .hero {
    background: var(--paper);
    border-bottom: 3px solid var(--ink);
    padding: 80px 32px 64px;
    text-align: center;
    position: relative;
    overflow: hidden;
  }
  .hero::before {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0; right: 0;
    height: 8px;
    background: repeating-linear-gradient(
      90deg,
      var(--accent) 0 16px,
      var(--ink) 16px 32px
    );
  }
  .hero-inner { max-width: 900px; margin: 0 auto; }
  .hero-eyebrow {
    font-family: 'JetBrains Mono', monospace;
    font-size: 13px;
    text-transform: uppercase;
    letter-spacing: 0.15em;
    color: var(--accent);
    margin-bottom: 24px;
  }
  .hero h1 {
    font-family: 'Syne', sans-serif;
    font-weight: 700;
    font-size: clamp(36px, 5vw, 64px);
    line-height: 1.25;
    letter-spacing: -0.02em;
    margin-bottom: 24px;
    padding-bottom: 4px;
    color: #2D2D33;
  }
  .hero h1 .accent { color: var(--accent); display: block; padding-bottom: 14px; }
  .hero-sub {
    font-size: 19px;
    color: var(--muted);
    max-width: 640px;
    margin: 0 auto 40px;
  }
  .hero-stats {
    display: flex;
    justify-content: center;
    gap: 0;
    flex-wrap: wrap;
    border: 2px solid var(--ink);
    box-shadow: 6px 6px 0 var(--accent);
    background: var(--paper);
    max-width: 720px;
    margin: 0 auto;
  }
  .stat {
    padding: 20px 28px;
    border-right: 2px solid var(--ink);
    text-align: left;
    flex: 1;
    min-width: 160px;
  }
  .stat:last-child { border-right: none; }
  .stat-num {
    font-family: 'Syne', sans-serif;
    font-weight: 800;
    font-size: 32px;
    letter-spacing: -0.02em;
    line-height: 1;
  }
  .stat-label {
    font-family: 'JetBrains Mono', monospace;
    font-size: 11px;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--muted);
    margin-top: 6px;
  }

  /* ===== LAYOUT ===== */
  .layout {
    max-width: 1100px;
    margin: 0 auto;
    padding: 48px 32px;
    display: grid;
    grid-template-columns: 220px 1fr;
    gap: 48px;
  }

  /* ===== TOC SIDEBAR ===== */
  .toc {
    position: sticky;
    top: 110px;
    align-self: start;
    border: 2px solid var(--ink);
    background: var(--paper);
    box-shadow: 4px 4px 0 var(--ink);
    max-height: calc(100vh - 130px);
    overflow-y: auto;
  }
  .toc-header {
    background: var(--ink);
    color: var(--paper);
    padding: 12px 16px;
    font-family: 'JetBrains Mono', monospace;
    font-size: 11px;
    text-transform: uppercase;
    letter-spacing: 0.15em;
    font-weight: 700;
  }
  .toc ol {
    list-style: none;
    padding: 12px 0;
    counter-reset: toc;
  }
  .toc li { counter-increment: toc; }
  .toc a {
    display: block;
    padding: 8px 16px;
    color: var(--ink);
    text-decoration: none;
    font-size: 14px;
    border-left: 3px solid transparent;
    transition: all 0.15s;
  }
  .toc a::before {
    content: counter(toc, decimal-leading-zero);
    font-family: 'JetBrains Mono', monospace;
    font-size: 11px;
    color: var(--muted);
    margin-right: 10px;
  }
  .toc a:hover {
    background: var(--bg);
    border-left-color: var(--accent);
  }
  .toc a.active {
    background: var(--bg);
    border-left-color: var(--accent);
    font-weight: 600;
  }

  /* ===== MAIN CONTENT ===== */
  main { min-width: 0; }

  section.step {
    background: var(--paper);
    border: 2px solid var(--ink);
    box-shadow: 6px 6px 0 var(--ink);
    margin-bottom: 48px;
    overflow: hidden;
  }

  .step-header {
    background: var(--ink);
    color: var(--paper);
    padding: 28px 32px;
    display: flex;
    align-items: baseline;
    gap: 20px;
    flex-wrap: wrap;
  }
  .step-num {
    font-family: 'JetBrains Mono', monospace;
    font-size: 14px;
    color: var(--accent-soft);
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.1em;
  }
  .step-header h2 {
    font-family: 'Syne', sans-serif;
    font-weight: 700;
    font-size: 32px;
    letter-spacing: -0.02em;
    line-height: 1.1;
  }
  .step-body { padding: 32px; }

  /* ===== TYPOGRAPHY ===== */
  p { margin-bottom: 16px; color: #222; }

  h3 {
    font-family: 'Syne', sans-serif;
    font-weight: 700;
    font-size: 22px;
    letter-spacing: -0.01em;
    margin: 32px 0 12px;
    color: var(--ink);
    padding-bottom: 6px;
    border-bottom: 2px solid var(--ink);
  }
  h3:first-child { margin-top: 0; }

  h4 {
    font-family: 'Syne', sans-serif;
    font-weight: 700;
    font-size: 17px;
    margin: 24px 0 10px;
    color: var(--accent);
  }

  code.inline {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.88em;
    background: #E8F0FF;
    padding: 2px 6px;
    border: 1px solid #B8D0FF;
    border-radius: 2px;
    color: var(--accent-dark);
  }

  ul, ol {
    margin: 0 0 16px 24px;
    color: #222;
  }
  li { margin-bottom: 8px; }

  /* ===== CODE BLOCKS ===== */
  .code-wrap {
    margin: 20px 0;
    border: 2px solid var(--ink);
    box-shadow: 4px 4px 0 var(--accent);
    background: var(--code-bg);
    overflow: hidden;
  }
  .code-bar {
    background: #2A2A2A;
    color: #999;
    padding: 8px 16px;
    font-family: 'JetBrains Mono', monospace;
    font-size: 11px;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid #444;
  }
  .code-bar .lang { color: var(--accent-soft); font-weight: 700; }
  .copy-btn {
    background: transparent;
    border: 1px solid #555;
    color: #CCC;
    padding: 3px 10px;
    font-family: 'JetBrains Mono', monospace;
    font-size: 10px;
    cursor: pointer;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    transition: all 0.15s;
  }
  .copy-btn:hover {
    background: var(--accent);
    color: white;
    border-color: var(--accent);
  }
  .copy-btn.copied {
    background: #4CAF93;
    color: white;
    border-color: #4CAF93;
  }
  pre {
    padding: 20px;
    overflow-x: auto;
    font-family: 'JetBrains Mono', monospace;
    font-size: 13px;
    line-height: 1.55;
    color: var(--code-text);
  }
  pre .k { color: #C586C0; }
  pre .s { color: #CE9178; }
  pre .c { color: #6A9955; font-style: italic; }
  pre .t { color: #4EC9B0; }
  pre .a { color: #9CDCFE; }
  pre .n { color: #B5CEA8; }
  pre .f { color: #DCDCAA; }

  /* ===== CALLOUTS ===== */
  .callout {
    border: 2px solid var(--ink);
    padding: 16px 20px;
    margin: 20px 0;
    background: var(--tip-bg);
    box-shadow: 4px 4px 0 var(--ink);
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 16px;
    align-items: start;
  }
  .callout-icon {
    font-family: 'Syne', sans-serif;
    font-weight: 800;
    font-size: 14px;
    background: var(--ink);
    color: var(--accent-soft);
    padding: 4px 10px;
    letter-spacing: 0.1em;
    white-space: nowrap;
  }
  .callout p:last-child { margin-bottom: 0; }
  .callout.warn { background: var(--warn-bg); }
  .callout.warn .callout-icon { color: #FF6B6B; }
  .callout.note { background: #F0F6FF; }
  .callout.note .callout-icon { color: var(--accent-soft); }

  /* ===== CHECKLIST ===== */
  .checklist {
    list-style: none;
    margin: 16px 0;
    padding: 0;
    border: 2px solid var(--ink);
    background: var(--paper);
  }
  .checklist li {
    padding: 14px 18px;
    border-bottom: 1px solid #DDD;
    display: grid;
    grid-template-columns: 28px 1fr;
    gap: 12px;
    align-items: center;
    cursor: pointer;
    transition: background 0.15s;
    margin: 0;
  }
  .checklist li:last-child { border-bottom: none; }
  .checklist li:hover { background: var(--bg); }
  .checklist .box {
    width: 22px;
    height: 22px;
    border: 2px solid var(--ink);
    background: var(--paper);
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: 'Syne', sans-serif;
    font-weight: 800;
    color: transparent;
  }
  .checklist li.done { background: #E8F5E9; }
  .checklist li.done .box {
    background: #4CAF93;
    color: white;
    border-color: #4CAF93;
  }
  .checklist li.done .box::after { content: '✓'; }
  .checklist li.done span:not(.box) {
    text-decoration: line-through;
    color: var(--muted);
  }

  /* ===== PALETTE TABLE ===== */
  .palette {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 0;
    border: 2px solid var(--ink);
    margin: 20px 0;
  }
  .swatch {
    border-right: 2px solid var(--ink);
    border-bottom: 2px solid var(--ink);
    padding: 16px;
    background: var(--paper);
  }
  .swatch-color {
    width: 100%;
    height: 60px;
    border: 1px solid var(--ink);
    margin-bottom: 10px;
  }
  .sc-1 { background: #1A1A1A; }
  .sc-2 { background: #2D2D33; }
  .sc-3 { background: #F4F4F6; }
  .sc-4 { background: #0066FF; }
  .sc-5 { background: #4D8FFF; }
  .sc-6 { background: #0048B8; }
  .sc-7 { background: #FFD814; }
  .sc-8 { background: #FFA41C; }
  .swatch-hex {
    font-family: 'JetBrains Mono', monospace;
    font-size: 13px;
    font-weight: 700;
  }
  .swatch-name {
    font-size: 12px;
    color: var(--muted);
    margin-top: 4px;
  }

  /* ===== FOOTER ===== */
  footer.bottom {
    background: var(--ink);
    color: var(--paper);
    padding: 48px 32px;
    margin-top: 64px;
    border-top: 8px solid var(--accent);
  }
  .footer-inner {
    max-width: 1100px;
    margin: 0 auto;
    text-align: center;
  }
  .footer-brand {
    font-family: 'Syne', sans-serif;
    font-weight: 800;
    font-size: 32px;
    letter-spacing: -0.03em;
    margin-bottom: 12px;
  }
  .footer-brand span { color: var(--accent-soft); }
  .footer-meta {
    font-family: 'JetBrains Mono', monospace;
    font-size: 12px;
    color: #888;
    text-transform: uppercase;
    letter-spacing: 0.1em;
  }

  /* ===== RESPONSIVE ===== */
  @media (max-width: 900px) {
    .layout {
      grid-template-columns: 1fr;
      padding: 24px 16px;
    }
    .toc {
      position: static;
      max-height: none;
    }
    .step-body { padding: 24px 20px; }
    .hero { padding: 56px 20px 48px; }
    .step-header { padding: 20px 24px; }
    .step-header h2 { font-size: 26px; }
  }