:root {
    color-scheme: light;
    --bg: #ffffff;
    --ink: #0e1526;
    --ink-soft: #55607a;
    --muted: #8a93a8;
    --hairline: #e6e8ee;
    --accent: #3452d1;
    --accent-soft: #eef1fa;
    --band: #0d1526;
    --band-ink: #f5f6fa;
    --band-muted: #8f9ab8;
    --surface: #f8f9fc;
    --good: #0ca30c;
    --warning: #fab219;
    --warning-ink: #8a6412;
    --serious: #ec835a;
    --critical: #d03b3b;
    --font-serif: Georgia, "Iowan Old Style", "Times New Roman", serif;
    --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
    --font-mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  }
  @media (prefers-color-scheme: dark) {
    :root:where(:not([data-theme="light"])) {
      color-scheme: dark;
      --bg: #0b0e16;
      --ink: #f2f3f7;
      --ink-soft: #b7bdd0;
      --muted: #7d8496;
      --hairline: #232838;
      --accent: #7189f2;
      --accent-soft: #171d33;
      --band: #10141f;
      --band-ink: #f5f6fa;
      --band-muted: #8f9ab8;
      --surface: #12151f;
      --warning-ink: #f6cf8a;
    }
  }
  :root[data-theme="dark"] {
    color-scheme: dark;
    --bg: #0b0e16;
    --ink: #f2f3f7;
    --ink-soft: #b7bdd0;
    --muted: #7d8496;
    --hairline: #232838;
    --accent: #7189f2;
    --accent-soft: #171d33;
    --band: #10141f;
    --band-ink: #f5f6fa;
    --band-muted: #8f9ab8;
    --surface: #12151f;
    --warning-ink: #f6cf8a;
  }

  * { box-sizing: border-box; }
  html { scroll-behavior: smooth; }
  @media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
    * { transition: none !important; animation: none !important; }
  }
  body {
    margin: 0;
    background: var(--bg);
    color: var(--ink);
    font-family: var(--font-sans);
    -webkit-font-smoothing: antialiased;
  }
  .wrap { max-width: 1120px; margin: 0 auto; padding: 0 32px; }
  ::selection { background: var(--accent-soft); color: var(--accent); }

  a { color: var(--accent); }
  :focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

  /* ---------- header ---------- */
  header.site {
    position: sticky; top: 0; z-index: 20;
    background: var(--bg);
    border-bottom: 1px solid var(--hairline);
  }
  .header-row {
    display: flex; align-items: center; justify-content: space-between;
    height: 84px; gap: 24px;
  }
  .logo {
    display: flex; align-items: center; gap: 14px;
    font-family: var(--font-serif); font-size: 17px; letter-spacing: 0.03em;
    white-space: nowrap;
  }
  /* The source PNG is a white/outlined wordmark with a soft glow baked in:
     it reads crisp on a dark ground and as a fine outlined mark on a light
     one (checked by compositing both ways) -- no filter needed either way. */
  .logo-mark-img { height: 44px; width: auto; display: block; }
  .logo-divider { width: 1px; height: 30px; background: var(--hairline); flex-shrink: 0; }
  .logo .sub { font-family: var(--font-sans); font-size: 10px; color: var(--muted); letter-spacing: 0.08em; display: block; }
  nav.main {
    display: flex; gap: 28px; flex-wrap: wrap; justify-content: flex-end;
    font-size: 14.5px;
  }
  nav.main a {
    color: var(--ink); text-decoration: none; padding-bottom: 4px;
    border-bottom: 2px solid transparent;
  }
  nav.main a:hover, nav.main a:focus-visible { border-color: var(--accent); color: var(--accent); }

  /* ---------- dark band (reused per stage) ---------- */
  .band {
    background: var(--band); color: var(--band-ink);
  }
  .band-inner {
    display: flex; align-items: baseline; justify-content: space-between;
    flex-wrap: wrap; gap: 16px; padding: 28px 0;
  }
  .band-left { display: flex; align-items: baseline; gap: 18px; }
  .band-num { font-family: var(--font-serif); font-size: 38px; line-height: 1; color: var(--band-ink); }
  .band-label { font-size: 12.5px; letter-spacing: 0.12em; text-transform: uppercase; color: var(--band-muted); }
  .band-tag { font-size: 12.5px; letter-spacing: 0.1em; text-transform: uppercase; color: var(--band-muted); text-align: right; }
  .band-tag b { font-family: var(--font-serif); font-size: 22px; color: var(--band-ink); font-style: italic; font-weight: 400; letter-spacing: 0; text-transform: none; margin-right: 10px; }

  .hero-band .band-inner { padding: 40px 0; }

  /* ---------- why section ---------- */
  .why { padding: 96px 0; }
  .why-grid {
    display: grid; grid-template-columns: 1.1fr 1fr 1fr; gap: 0;
    align-items: start;
  }
  .why-grid > div { padding: 0 40px; }
  .why-grid > div:first-child { padding-left: 0; }
  .why-grid > div:not(:first-child) { border-left: 1px solid var(--hairline); }
  .eyebrow {
    font-size: 12.5px; letter-spacing: 0.14em; text-transform: uppercase; color: var(--muted);
    margin: 0 0 18px;
  }
  h1.display {
    font-family: var(--font-serif); font-weight: 400; font-size: 46px; line-height: 1.12;
    margin: 0 0 20px; color: var(--ink); text-wrap: balance;
  }
  .lede { font-size: 17px; color: var(--ink-soft); line-height: 1.6; max-width: 46ch; margin: 0; }
  .icon-circle {
    width: 46px; height: 46px; border-radius: 50%; border: 1.5px solid var(--accent);
    display: flex; align-items: center; justify-content: center; margin-bottom: 22px; color: var(--accent);
  }
  h3.col-head { font-family: var(--font-serif); font-weight: 400; font-size: 22px; margin: 0 0 12px; color: var(--ink); }
  .col-body { font-size: 15px; color: var(--ink-soft); line-height: 1.6; margin: 0; }

  /* ---------- stage sections ---------- */
  .stage { padding: 64px 0 88px; border-bottom: 1px solid var(--hairline); }
  .stage:last-of-type { border-bottom: none; }
  .stage-head { max-width: 62ch; margin-bottom: 40px; }
  .stage-head h2 { font-family: var(--font-serif); font-weight: 400; font-size: 32px; margin: 18px 0 14px; text-wrap: balance; }
  .stage-head p { font-size: 15.5px; color: var(--ink-soft); line-height: 1.65; margin: 0; }
  .stage-columns { display: grid; grid-template-columns: 1fr; gap: 40px; }

  /* stat tiles */
  .stat-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 1px; background: var(--hairline); border: 1px solid var(--hairline); margin: 0 0 8px; }
  .stat-tile { background: var(--bg); padding: 22px 20px; }
  .stat-tile .num { font-family: var(--font-mono); font-variant-numeric: tabular-nums; font-size: 28px; color: var(--ink); display: block; }
  .stat-tile .lbl { font-size: 12px; color: var(--muted); letter-spacing: 0.04em; margin-top: 6px; display: block; }

  /* before/after callout */
  .versus { display: flex; align-items: center; gap: 22px; flex-wrap: wrap; margin: 8px 0 4px; }
  .versus .v-item { text-align: center; }
  .versus .v-num { font-family: var(--font-mono); font-variant-numeric: tabular-nums; font-size: 34px; color: var(--ink); }
  .versus .v-num.before { color: var(--critical); }
  .versus .v-num.after { color: var(--good); }
  .versus .v-lbl { font-size: 12px; color: var(--muted); margin-top: 4px; }
  .versus .v-arrow { font-family: var(--font-serif); font-size: 26px; color: var(--muted); }

  /* bar chart */
  .chart-title { font-size: 13px; letter-spacing: 0.04em; color: var(--muted); text-transform: uppercase; margin: 0 0 16px; }
  .bar-chart { display: flex; flex-direction: column; gap: 10px; }
  .bar-row {
    display: grid; grid-template-columns: 168px 1fr 70px; align-items: center; gap: 12px;
    position: relative; padding: 5px 0; cursor: default;
  }
  .bar-label { font-size: 13.5px; color: var(--ink-soft); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
  .bar-track { height: 14px; background: var(--surface); border-radius: 2px; overflow: hidden; }
  .bar-fill { height: 100%; min-width: 3px; background: var(--accent); border-radius: 2px 4px 4px 2px; }
  .bar-value { font-family: var(--font-mono); font-variant-numeric: tabular-nums; font-size: 13px; text-align: right; color: var(--ink); }
  .chip {
    display: inline-flex; align-items: center; gap: 5px; font-size: 10.5px; letter-spacing: 0.03em;
    padding: 2px 7px; border-radius: 3px; margin-left: 8px; white-space: nowrap;
  }
  .chip::before { content: ""; width: 6px; height: 6px; border-radius: 50%; display: inline-block; }
  .chip.high { background: color-mix(in srgb, var(--serious) 16%, transparent); color: var(--serious); }
  .chip.high::before { background: var(--serious); }
  .chip.medium { background: color-mix(in srgb, var(--warning) 20%, transparent); color: var(--warning-ink); }
  .chip.medium::before { background: var(--warning); }

  [data-tooltip] { position: relative; }
  [data-tooltip]:hover::after, [data-tooltip]:focus-visible::after {
    content: attr(data-tooltip);
    position: absolute; left: 168px; bottom: calc(100% + 4px);
    background: var(--ink); color: var(--bg); font-family: var(--font-sans);
    font-size: 12px; padding: 6px 10px; border-radius: 4px; white-space: nowrap;
    z-index: 5; box-shadow: 0 4px 14px rgba(0,0,0,0.18);
  }

  /* line chart */
  .line-chart-wrap { overflow-x: auto; }
  svg.linechart { display: block; }
  .lc-grid { stroke: var(--hairline); stroke-width: 1; }
  .lc-area { fill: var(--accent); opacity: 0.12; }
  .lc-line { fill: none; stroke: var(--accent); stroke-width: 2; }
  .lc-point { fill: var(--bg); stroke: var(--accent); stroke-width: 2; cursor: default; }
  .lc-point.emph { fill: var(--accent); r: 6; }
  .lc-point:hover, .lc-point:focus-visible { r: 7; }
  .lc-label { font-family: var(--font-mono); font-size: 11px; fill: var(--muted); }
  .lc-value-label { font-family: var(--font-mono); font-size: 12px; fill: var(--ink); font-variant-numeric: tabular-nums; }

  /* tables */
  .table-wrap { overflow-x: auto; border: 1px solid var(--hairline); }
  table.data { border-collapse: collapse; width: 100%; font-size: 13.5px; min-width: 640px; }
  table.data th {
    text-align: left; font-size: 11px; letter-spacing: 0.06em; text-transform: uppercase; color: var(--muted);
    padding: 12px 16px; border-bottom: 1px solid var(--hairline); background: var(--surface); white-space: nowrap;
  }
  table.data td { padding: 12px 16px; border-bottom: 1px solid var(--hairline); color: var(--ink-soft); vertical-align: top; }
  table.data tr:last-child td { border-bottom: none; }
  table.data td.mono, table.data td b { font-family: var(--font-mono); color: var(--ink); font-variant-numeric: tabular-nums; }
  table.data td.ink { color: var(--ink); }

  /* mermaid container */
  .diagram-card { border: 1px solid var(--hairline); background: var(--surface); padding: 24px; overflow-x: auto; }
  .diagram-caption { font-size: 12.5px; color: var(--muted); margin-top: 10px; }

  .status-note {
    display: flex; gap: 10px; align-items: flex-start; font-size: 13.5px; color: var(--ink-soft);
    background: var(--surface); border: 1px solid var(--hairline); padding: 14px 16px; margin-top: 20px;
  }
  .status-note b { color: var(--ink); }

  .checklist { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 10px; }
  .checklist li { display: flex; gap: 10px; align-items: flex-start; font-size: 14px; color: var(--ink-soft); }
  .checklist .ok { color: var(--good); font-family: var(--font-mono); flex-shrink: 0; }

  .status-grid { display: flex; flex-direction: column; gap: 1px; background: var(--hairline); border: 1px solid var(--hairline); }
  .status-item { background: var(--bg); display: flex; align-items: center; justify-content: space-between; padding: 12px 16px; font-size: 13.5px; }
  .status-item .name { color: var(--ink); }
  .status-item .pill { font-size: 11px; letter-spacing: 0.04em; padding: 3px 9px; border-radius: 20px; display: inline-flex; align-items: center; gap: 6px; }
  .status-item .pill::before { content:""; width: 6px; height: 6px; border-radius: 50%; }
  .status-item .pill.done { color: var(--good); background: color-mix(in srgb, var(--good) 14%, transparent); }
  .status-item .pill.done::before { background: var(--good); }
  .status-item .pill.todo { color: var(--muted); background: var(--surface); }
  .status-item .pill.todo::before { background: var(--muted); }

  code.inline { font-family: var(--font-mono); background: var(--surface); padding: 1px 6px; border-radius: 3px; font-size: 0.92em; color: var(--ink); }

  footer.site { border-top: 1px solid var(--hairline); padding: 48px 0 64px; }
  footer.site .foot-grid { display: flex; justify-content: space-between; gap: 24px; flex-wrap: wrap; font-size: 13.5px; color: var(--muted); }
  footer.site a { color: var(--ink-soft); }

  /* ---------- inference simulation ---------- */
  .preset-grid { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 24px; }
  .preset-btn {
    font-family: var(--font-sans); font-size: 13px; padding: 8px 14px; border-radius: 20px;
    border: 1px solid var(--hairline); background: var(--bg); color: var(--ink-soft); cursor: pointer;
  }
  .preset-btn:hover, .preset-btn:focus-visible { border-color: var(--accent); color: var(--accent); }
  .preset-btn.active { background: var(--accent); border-color: var(--accent); color: #fff; }

  .inference-form fieldset {
    border: 1px solid var(--hairline); border-radius: 4px; padding: 16px 18px 18px; margin: 0 0 18px;
    display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 14px 16px;
  }
  .inference-form legend {
    font-size: 11px; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); padding: 0 6px;
  }
  .inference-form label {
    display: flex; flex-direction: column; gap: 6px; font-size: 13px; color: var(--ink-soft);
  }
  .inference-form input, .inference-form select {
    font-family: var(--font-mono); font-size: 13.5px; color: var(--ink); background: var(--bg);
    border: 1px solid var(--hairline); border-radius: 3px; padding: 8px 10px; width: 100%;
  }
  .inference-form input:focus-visible, .inference-form select:focus-visible { border-color: var(--accent); }

  .btn-primary {
    font-family: var(--font-sans); font-size: 14px; font-weight: 600; color: #fff; background: var(--ink);
    border: none; border-radius: 4px; padding: 12px 22px; cursor: pointer;
  }
  .btn-primary:hover, .btn-primary:focus-visible { background: var(--accent); }
  .btn-primary:disabled { opacity: 0.5; cursor: wait; }

  .inference-result { border: 1px solid var(--hairline); padding: 20px; min-height: 120px; }
  .inference-result .result-score { font-family: var(--font-mono); font-size: 42px; font-variant-numeric: tabular-nums; color: var(--ink); line-height: 1; }
  .inference-result .result-flag {
    display: inline-flex; align-items: center; gap: 6px; font-size: 12px; letter-spacing: 0.04em;
    padding: 4px 10px; border-radius: 20px; margin: 10px 0 16px;
  }
  .inference-result .result-flag::before { content: ""; width: 7px; height: 7px; border-radius: 50%; }
  .inference-result .result-flag.anomaly { background: color-mix(in srgb, var(--critical) 14%, transparent); color: var(--critical); }
  .inference-result .result-flag.anomaly::before { background: var(--critical); }
  .inference-result .result-flag.normal { background: color-mix(in srgb, var(--good) 14%, transparent); color: var(--good); }
  .inference-result .result-flag.normal::before { background: var(--good); }
  .inference-result .result-percentile { font-size: 13px; color: var(--muted); margin-bottom: 14px; }
  .inference-result .result-percentile b { font-family: var(--font-mono); color: var(--ink); }
  .inference-result .result-bar-track { height: 8px; background: var(--surface); border-radius: 4px; overflow: hidden; margin-bottom: 16px; }
  .inference-result .result-bar-fill { height: 100%; background: var(--accent); }
  .inference-result p.col-body { margin: 0; }
  .inference-result.is-error { color: var(--critical); }

  .status-note.ok { border-color: color-mix(in srgb, var(--good) 30%, var(--hairline)); }
  .status-note.error { border-color: color-mix(in srgb, var(--critical) 30%, var(--hairline)); color: var(--critical); }

  @media (max-width: 860px) {
    .why-grid { grid-template-columns: 1fr; }
    .why-grid > div { padding: 32px 0 0 !important; border-left: none !important; border-top: 1px solid var(--hairline); }
    .why-grid > div:first-child { border-top: none; padding-top: 0 !important; }
    h1.display { font-size: 34px; }
    .bar-row { grid-template-columns: 110px 1fr 60px; }
    .bar-label { font-size: 12px; }
    [data-tooltip]:hover::after, [data-tooltip]:focus-visible::after { left: 110px; white-space: normal; max-width: 220px; }
    nav.main { display: none; }
  }