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

    :root {
      --bg: #0f1216;
      --bg2: #161b22;
      --bg3: #1c2128;
      --line: rgba(201,209,217,0.08);
      --text: #c9d1d9;
      --muted: rgba(201,209,217,0.45);
      --accent: #c9d1d9;
      --accent-dim: rgba(201,209,217,0.15);
      --green: #7ee787;
      --font-display: 'Syne', sans-serif;
      --font-serif: 'Instrument Serif', serif;
      --font-mono: 'JetBrains Mono', monospace;

      /* site-shell aliases — nav/footer reference these */
      --void: #0f1216;
      --void-mid: #161b22;
      --void-deep: #0a0d10;
      --ash: #c9d1d9;
      --ash-dim: rgba(201,209,217,0.4);
      --ash-ghost: rgba(201,209,217,0.08);
      --ash-faint: rgba(201,209,217,0.03);
      --font-body: 'Instrument Serif', serif;
    }

    html { scroll-behavior: smooth; }

    body {
      background: var(--bg);
      color: var(--text);
      font-family: var(--font-display);
      font-size: 15px;
      line-height: 1.7;
      min-height: 100vh;
    }

    /* noise overlay */
    body::before {
      content: '';
      position: fixed;
      inset: 0;
      background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='0.04'/%3E%3C/svg%3E");
      pointer-events: none;
      z-index: 999;
      opacity: 0.35;
    }

    /* ── Layout ── */
    .page-wrap {
      max-width: 1100px;
      margin: 0 auto;
      padding: 0 2rem;
    }

    /* ── Hero ── */
    .hero {
      padding: 7rem 0 4rem;
      border-bottom: 1px solid var(--line);
    }

    .hero-label {
      font-family: var(--font-mono);
      font-size: 0.7rem;
      letter-spacing: 0.18em;
      text-transform: uppercase;
      color: var(--muted);
      margin-bottom: 1.5rem;
      display: flex;
      align-items: center;
      gap: 0.75rem;
    }

    .hero-label::before {
      content: '';
      display: inline-block;
      width: 2rem;
      height: 1px;
      background: var(--muted);
    }

    .hero h1 {
      font-family: var(--font-serif);
      font-size: clamp(2.4rem, 5vw, 4rem);
      font-weight: 400;
      font-style: italic;
      line-height: 1.15;
      color: var(--accent);
      margin-bottom: 1.5rem;
      max-width: 700px;
    }

    .hero-sub {
      color: var(--muted);
      font-size: 0.95rem;
      max-width: 540px;
      line-height: 1.8;
    }

    .hero-meta {
      margin-top: 2.5rem;
      display: flex;
      flex-wrap: wrap;
      gap: 2rem;
    }

    .meta-item {
      display: flex;
      flex-direction: column;
      gap: 0.2rem;
    }

    .meta-item .label {
      font-family: var(--font-mono);
      font-size: 0.65rem;
      letter-spacing: 0.15em;
      text-transform: uppercase;
      color: var(--muted);
    }

    .meta-item .value {
      font-size: 0.85rem;
      color: var(--text);
    }

    /* ── Two-col layout ── */
    .content-grid {
      display: grid;
      grid-template-columns: 220px 1fr;
      gap: 0;
      min-height: 100vh;
    }

    /* ── Sidebar ── */
    .sidebar {
      border-right: 1px solid var(--line);
      padding: 3rem 0 3rem;
      position: sticky;
      top: 0;
      height: 100vh;
      overflow-y: auto;
    }

    .sidebar-label {
      font-family: var(--font-mono);
      font-size: 0.6rem;
      letter-spacing: 0.2em;
      text-transform: uppercase;
      color: var(--muted);
      padding: 0 1.5rem 1rem;
      border-bottom: 1px solid var(--line);
      margin-bottom: 1rem;
    }

    .sidebar nav ul {
      list-style: none;
    }

    .sidebar nav ul li a {
      display: block;
      padding: 0.45rem 1.5rem;
      font-size: 0.8rem;
      color: var(--muted);
      text-decoration: none;
      transition: color 0.15s, padding-left 0.15s;
      border-left: 2px solid transparent;
      line-height: 1.5;
    }

    .sidebar nav ul li a:hover {
      color: var(--text);
      padding-left: 1.9rem;
      border-left-color: var(--line);
    }

    .sidebar nav ul li a.active {
      color: var(--text);
      border-left-color: var(--accent);
    }

    .sidebar-downloads {
      margin-top: 2rem;
      padding: 1rem 1.5rem;
      border-top: 1px solid var(--line);
    }

    .sidebar-downloads .label {
      font-family: var(--font-mono);
      font-size: 0.6rem;
      letter-spacing: 0.15em;
      text-transform: uppercase;
      color: var(--muted);
      margin-bottom: 0.75rem;
      display: block;
    }

    .dl-link {
      display: block;
      font-size: 0.75rem;
      font-family: var(--font-mono);
      color: var(--muted);
      text-decoration: none;
      padding: 0.3rem 0;
      border-bottom: 1px solid var(--line);
      transition: color 0.15s;
    }

    .dl-link:last-child { border-bottom: none; }
    .dl-link:hover { color: var(--text); }
    .dl-link.latest { color: var(--green); }
    .dl-link.latest:hover { color: var(--green); opacity: 0.8; }

    /* ── Main content ── */
    .main-content {
      padding: 3rem 3rem 6rem;
    }

    /* ── Section ── */
    .section {
      padding: 3rem 0;
      border-bottom: 1px solid var(--line);
    }

    .section:last-child { border-bottom: none; }

    .section-header {
      margin-bottom: 2rem;
    }

    .section-index {
      font-family: var(--font-mono);
      font-size: 0.65rem;
      letter-spacing: 0.15em;
      color: var(--muted);
      text-transform: uppercase;
      margin-bottom: 0.5rem;
    }

    .section h2 {
      font-family: var(--font-serif);
      font-size: 1.6rem;
      font-weight: 400;
      font-style: italic;
      color: var(--accent);
      line-height: 1.3;
    }

    .section h3 {
      font-family: var(--font-display);
      font-size: 0.8rem;
      font-weight: 600;
      letter-spacing: 0.08em;
      text-transform: uppercase;
      color: var(--muted);
      margin: 2rem 0 0.75rem;
    }

    .section p {
      color: var(--muted);
      font-size: 0.9rem;
      line-height: 1.8;
      margin-bottom: 0.75rem;
    }

    /* ── Todo list ── */
    .todo-list {
      list-style: none;
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 0.3rem 2rem;
    }

    .todo-list li {
      font-size: 0.85rem;
      color: var(--muted);
      padding: 0.4rem 0;
      border-bottom: 1px solid var(--line);
      display: flex;
      align-items: flex-start;
      gap: 0.6rem;
      line-height: 1.5;
    }

    .todo-list li::before {
      content: '—';
      color: var(--line);
      flex-shrink: 0;
      margin-top: 0.05em;
    }

    /* ── Code blocks ── */
    .code-block {
      position: relative;
      background: var(--bg2);
      border: 1px solid var(--line);
      border-radius: 4px;
      margin: 1rem 0;
      overflow: hidden;
    }

    .code-block-header {
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 0.5rem 1rem;
      border-bottom: 1px solid var(--line);
      background: var(--bg3);
    }

    .code-block-label {
      font-family: var(--font-mono);
      font-size: 0.65rem;
      letter-spacing: 0.1em;
      text-transform: uppercase;
      color: var(--muted);
    }

    .copy-btn {
      font-family: var(--font-mono);
      font-size: 0.65rem;
      letter-spacing: 0.1em;
      text-transform: uppercase;
      color: var(--muted);
      background: none;
      border: 1px solid var(--line);
      padding: 0.25rem 0.6rem;
      border-radius: 2px;
      cursor: pointer;
      transition: color 0.15s, border-color 0.15s;
    }

    .copy-btn:hover { color: var(--text); border-color: var(--muted); }
    .copy-btn.copied { color: var(--green); border-color: var(--green); }

    .code-block pre {
      font-family: var(--font-mono);
      font-size: 0.8rem;
      line-height: 1.75;
      padding: 1.25rem 1.25rem;
      overflow-x: auto;
      color: var(--text);
      white-space: pre;
    }

    .code-block pre code {
      font-family: inherit;
    }

    /* ── Expected output (collapsible) ── */
    .expected {
      margin-top: 0.5rem;
    }

    .expected summary {
      font-family: var(--font-mono);
      font-size: 0.7rem;
      letter-spacing: 0.1em;
      text-transform: uppercase;
      color: var(--muted);
      cursor: pointer;
      user-select: none;
      padding: 0.5rem 0;
      list-style: none;
      display: flex;
      align-items: center;
      gap: 0.5rem;
      transition: color 0.15s;
    }

    .expected summary:hover { color: var(--text); }

    .expected summary::before {
      content: '▶';
      font-size: 0.5rem;
      transition: transform 0.2s;
    }

    .expected[open] summary::before { transform: rotate(90deg); }

    /* ── Table ── */
    .data-table {
      width: 100%;
      border-collapse: collapse;
      font-size: 0.82rem;
      margin: 1rem 0;
    }

    .data-table th {
      font-family: var(--font-mono);
      font-size: 0.65rem;
      letter-spacing: 0.12em;
      text-transform: uppercase;
      color: var(--muted);
      text-align: left;
      padding: 0.6rem 0.75rem;
      border-bottom: 1px solid var(--line);
      font-weight: 400;
    }

    .data-table td {
      padding: 0.55rem 0.75rem;
      border-bottom: 1px solid var(--line);
      color: var(--muted);
      font-family: var(--font-mono);
      font-size: 0.78rem;
      vertical-align: top;
    }

    .data-table tr:hover td { color: var(--text); }

    .data-table code {
      font-family: var(--font-mono);
      font-size: 0.75rem;
      color: var(--text);
      background: var(--bg3);
      padding: 0.1em 0.35em;
      border-radius: 2px;
    }

    /* ── Image ── */
    .topology-img {
      width: 100%;
      border: 1px solid var(--line);
      border-radius: 4px;
      display: block;
    }

    /* ── Callout ── */
    .callout {
      background: var(--bg2);
      border-left: 2px solid var(--accent);
      padding: 0.85rem 1.1rem;
      border-radius: 0 4px 4px 0;
      font-size: 0.85rem;
      color: var(--muted);
      margin: 1.5rem 0;
      font-family: var(--font-mono);
      line-height: 1.6;
    }

    .callout code {
      color: var(--text);
    }

    /* ── Sources ── */
    .sources {
      margin-top: 1rem;
    }

    .sources summary {
      font-family: var(--font-mono);
      font-size: 0.7rem;
      letter-spacing: 0.1em;
      text-transform: uppercase;
      color: var(--muted);
      cursor: pointer;
      user-select: none;
      padding: 0.5rem 0;
      list-style: none;
      display: flex;
      align-items: center;
      gap: 0.5rem;
      transition: color 0.15s;
    }

    .sources summary:hover { color: var(--text); }
    .sources summary::before { content: '▶'; font-size: 0.5rem; transition: transform 0.2s; }
    .sources[open] summary::before { transform: rotate(90deg); }

    .sources-inner {
      padding: 1.25rem;
      background: var(--bg2);
      border: 1px solid var(--line);
      border-radius: 4px;
      margin-top: 0.5rem;
    }

    .sources-inner a {
      display: block;
      font-family: var(--font-mono);
      font-size: 0.72rem;
      color: var(--muted);
      text-decoration: none;
      padding: 0.3rem 0;
      border-bottom: 1px solid var(--line);
      transition: color 0.15s;
      word-break: break-all;
    }

    .sources-inner a:last-child { border-bottom: none; }
    .sources-inner a:hover { color: var(--text); }

    /* ── Step description ── */
    .step-desc {
      list-style: none;
      margin: 0.75rem 0 1.25rem;
    }

    .step-desc li {
      font-size: 0.85rem;
      color: var(--muted);
      padding: 0.3rem 0;
      display: flex;
      gap: 0.75rem;
      border-bottom: 1px solid var(--line);
      line-height: 1.5;
    }

    .step-desc li .num {
      font-family: var(--font-mono);
      font-size: 0.7rem;
      color: var(--line);
      flex-shrink: 0;
      padding-top: 0.15em;
      min-width: 1.5rem;
    }

    .step-desc code {
      font-family: var(--font-mono);
      font-size: 0.75rem;
      color: var(--text);
      background: var(--bg3);
      padding: 0.1em 0.35em;
      border-radius: 2px;
    }

    /* ── Responsive ── */
    @media (max-width: 820px) {
      .content-grid { grid-template-columns: 1fr; }
      .sidebar { position: static; height: auto; border-right: none; border-bottom: 1px solid var(--line); }
      .main-content { padding: 2rem 0 4rem; }
      .todo-list { grid-template-columns: 1fr; }
    }

    @media (max-width: 600px) {
      .page-wrap { padding: 0 1.25rem; }
      .hero { padding: 5rem 0 3rem; }
    }