:root {
      --surface-100: #17171C;
      --surface-200: #1E1E24;
      --surface-300: #202127;
      --border-100: #22242A;
      --border-200: #292C32;
      --text-primary: #C7C7CB;
      --text-secondary: #929296;
      --text-tertiary: #75757A;
      --primary: #5B8FFF;
      --tertiary: #BFFF5A;
      --ink: #0A0D16;

      --s-ddr4-3200: #0e88a4;
      --s-ddr5-32-4800: #119159;
      --s-ddr5-64-4800: #8962c2;
      --s-ddr5-32-5600: #ad680d;
      --s-ddr5-64-5600: #c64d3e;
      --status-error: #FF806E;
      --status-success: #19F79A;

      --font-sans: "IBM Plex Sans", system-ui, -apple-system, sans-serif;
      --font-mono: "IBM Plex Mono", ui-monospace, SFMono-Regular, monospace;

      --spacing-2xs: 4px;
      --spacing-xs: 8px;
      --spacing-sm: 12px;
      --spacing-md: 16px;
      --spacing-lg: 24px;
      --spacing-xl: 32px;
      --spacing-2xl: 48px;
      --spacing-3xl: 72px;
      --content-max: 1200px;
    }
    * { box-sizing: border-box; }
    html, body { margin: 0; padding: 0; }
    html, body { overflow-x: hidden; }
    body {
      background: var(--surface-100);
      color: var(--text-primary);
      font-family: var(--font-sans);
      font-size: 14px;
      line-height: 24px;
      width: 100%;
    }
    a { color: var(--primary); text-decoration: none; }
    a:hover { text-decoration: underline; }
    .wrap { max-width: var(--content-max); width: 100%; margin: 0 auto; padding: 0 var(--spacing-lg); }
    img, svg { max-width: 100%; }
    code, .mono { font-family: var(--font-mono); }

    /* ---- header ---- */
    header.site {
      border-bottom: 1px solid var(--border-100);
      padding: var(--spacing-md) 0;
    }
    header.site .wrap { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 4px 12px; }
    .brand { font-weight: 700; font-size: 16px; color: var(--text-primary); }
    .brand span { color: var(--text-tertiary); font-weight: 400; }
    .updated-badge {
      font-size: 11px; line-height: 16px; font-weight: 500; color: var(--text-tertiary);
      font-family: var(--font-mono);
    }

    /* ---- hero ---- */
    .hero { padding: var(--spacing-2xl) 0 var(--spacing-xl); }
    .hero h1 {
      font-size: 36px; line-height: 40px; font-weight: 700; letter-spacing: -0.5px;
      margin: 0 0 var(--spacing-sm); color: #F2F2F4;
      max-width: 820px;
    }
    .hero p.lede {
      font-size: 16px; line-height: 26px; color: var(--text-secondary);
      max-width: 680px; margin: 0;
    }
    .hero .lede strong { color: var(--text-primary); font-weight: 600; }

    /* ---- stat tiles ---- */
    .stats {
      display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--spacing-md);
      margin: var(--spacing-xl) 0;
    }
    .stat-tile {
      background: var(--surface-200); border: 1px solid var(--border-100); border-radius: 12px;
      padding: var(--spacing-md) var(--spacing-lg);
    }
    .stat-tile .label { font-size: 11px; line-height: 16px; font-weight: 500; color: var(--text-tertiary); text-transform: uppercase; letter-spacing: 0.04em; }
    .stat-tile .value { font-family: var(--font-mono); font-size: 26px; font-weight: 500; color: #F2F2F4; margin-top: var(--spacing-2xs); }
    .stat-tile .delta { font-size: 13px; margin-top: var(--spacing-2xs); font-family: var(--font-mono); }
    .delta.up { color: var(--status-error); }
    .delta.down { color: var(--status-success); }
    .delta.flat { color: var(--text-tertiary); }

    /* ---- chart card ---- */
    .card {
      background: var(--surface-200); border: 1px solid var(--border-100); border-radius: 16px;
      padding: var(--spacing-lg); margin-bottom: var(--spacing-xl);
    }
    .card h2 { font-size: 18px; line-height: 24px; font-weight: 700; margin: 0 0 var(--spacing-xs); color: #F2F2F4; }
    .controls {
      display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between;
      gap: var(--spacing-md); margin-bottom: var(--spacing-md);
    }
    .legend { display: flex; flex-wrap: wrap; gap: var(--spacing-sm); }
    .legend-item {
      display: flex; align-items: center; gap: 6px; font-size: 13px; color: var(--text-secondary);
      cursor: pointer; padding: 4px 10px 4px 6px; border-radius: 999px; border: 1px solid transparent;
      background: transparent; font-family: var(--font-sans); user-select: none;
    }
    .legend-item.off { opacity: 0.35; }
    .legend-item:hover { border-color: var(--border-200); }
    .legend-dot { width: 10px; height: 10px; border-radius: 50%; flex: none; }

    .seg { display: flex; gap: 2px; background: var(--surface-300); border-radius: 999px; padding: 2px; }
    .seg button, .seg a {
      font-family: var(--font-sans); font-size: 12px; font-weight: 500; color: var(--text-secondary);
      background: transparent; border: none; padding: 6px 12px; border-radius: 999px; cursor: pointer;
      text-decoration: none; display: inline-block; line-height: 1.4;
    }
    .seg button.active, .seg a.active { background: var(--tertiary); color: var(--ink); font-weight: 600; }
    .mode-bar { display: flex; justify-content: center; padding-top: var(--spacing-xl); }
    .mode-seg { padding: 4px; }
    .mode-seg a { font-size: 15px; padding: 8px 22px; }

    .chart-wrap { position: relative; }
    svg.chart { display: block; width: 100%; height: auto; overflow: visible; }
    .gridline { stroke: var(--border-100); stroke-width: 1; shape-rendering: crispEdges; }
    .axis-label { fill: var(--text-tertiary); font-family: var(--font-mono); font-size: 11px; }
    .series-line { fill: none; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }
    .series-point { stroke: var(--surface-200); stroke-width: 2; }
    .series-point.low-sample { fill-opacity: 0.45; }
    .end-label { font-family: var(--font-mono); font-size: 12px; font-weight: 500; }
    .crosshair-line { stroke: var(--border-200); stroke-width: 1; }
    .tooltip {
      position: absolute; pointer-events: none; background: var(--surface-300);
      border: 1px solid var(--border-200); border-radius: 8px; padding: var(--spacing-sm) var(--spacing-md);
      font-size: 12px; color: var(--text-primary); box-shadow: 0 4px 16px rgba(0,0,0,0.4);
      display: none; white-space: nowrap; z-index: 5;
    }
    .tooltip .t-date { font-family: var(--font-mono); color: var(--text-tertiary); margin-bottom: 4px; }
    .tooltip .t-row { display: flex; align-items: center; gap: 6px; margin-top: 2px; }
    .tooltip .t-dot { width: 8px; height: 8px; border-radius: 50%; flex: none; }
    .tooltip .t-val { font-family: var(--font-mono); margin-left: auto; padding-left: 12px; }

    .table-toggle {
      font-size: 12px; color: var(--text-secondary); background: none; border: 1px solid var(--border-200);
      border-radius: 999px; padding: 6px 12px; cursor: pointer; font-family: var(--font-sans);
      margin-top: var(--spacing-md);
    }
    .table-toggle:hover { border-color: var(--primary); color: var(--text-primary); }
    table.data-table { width: 100%; border-collapse: collapse; margin-top: var(--spacing-md); font-size: 13px; display: none; }
    table.data-table.visible { display: table; }
    table.data-table th, table.data-table td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--border-100); }
    table.data-table th { color: var(--text-tertiary); font-weight: 500; text-transform: uppercase; font-size: 11px; letter-spacing: 0.03em; }
    table.data-table td { color: var(--text-primary); }
    table.data-table td.num { font-family: var(--font-mono); }
    .low-n { color: var(--text-tertiary); }

    /* ---- prose sections ---- */
    section.prose { margin-bottom: var(--spacing-2xl); }
    section.prose h2 { font-size: 22px; line-height: 24px; font-weight: 700; color: #F2F2F4; margin: 0 0 var(--spacing-md); }
    section.prose h3 { font-size: 15px; line-height: 24px; font-weight: 600; color: var(--text-primary); margin: var(--spacing-lg) 0 var(--spacing-2xs); }
    section.prose p { color: var(--text-secondary); margin: 0 0 var(--spacing-md); max-width: 760px; }
    section.prose ul { color: var(--text-secondary); max-width: 760px; padding-left: 20px; }
    section.prose li { margin-bottom: var(--spacing-2xs); }
    section.prose a { color: var(--primary); }
    .source-tier-note {
      display: inline-flex; align-items: center; gap: 6px; font-size: 12px; font-family: var(--font-mono);
      color: var(--text-tertiary); background: var(--surface-200); border: 1px solid var(--border-100);
      border-radius: 999px; padding: 4px 10px; margin-right: var(--spacing-sm); margin-bottom: var(--spacing-sm);
    }

    .faq-item { border-bottom: 1px solid var(--border-100); padding: var(--spacing-md) 0; max-width: 760px; }
    .faq-item summary { cursor: pointer; font-weight: 600; color: var(--text-primary); font-size: 15px; }
    .faq-item p { margin-top: var(--spacing-sm); }

    /* ---- footer ---- */
    footer.site {
      border-top: 1px solid var(--border-100); padding: var(--spacing-xl) 0; margin-top: var(--spacing-2xl);
    }
    footer.site .wrap { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: var(--spacing-md); }
    footer.site p { font-size: 12px; color: var(--text-tertiary); margin: 0; }
    footer.site a { color: var(--text-tertiary); }

    @media (max-width: 767px) {
      .stats { grid-template-columns: 1fr; }
      .hero h1 { font-size: 28px; line-height: 32px; }
      .controls { flex-direction: column; align-items: flex-start; }
    }