:root {
    --paper: #f6f8f7;
    --card: #ffffff;
    --ink: #1a2b2a;
    --muted: #5c6f6c;
    --line: #dce4e2;
    --teal: #0e6e66;
    --teal-soft: #e3efed;
    --gold: #a06b1f;
    --gold-soft: #f5ead6;
    --good: #2c7a4b;
    --bad: #a4433b;
    --bad-soft: #f6e7e5;
    --cipher: #7b8a87;
    --mono: ui-monospace, "SF Mono", SFMono-Regular, Menlo, Consolas, monospace;
    --serif: "Iowan Old Style", "Palatino Linotype", Palatino, Charter, Georgia, serif;
    --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  }
  @media (prefers-color-scheme: dark) {
    :root {
      --paper: #101716;
      --card: #17201f;
      --ink: #e5ecea;
      --muted: #93a5a1;
      --line: #2a3634;
      --teal: #4fb3a8;
      --teal-soft: #16302d;
      --gold: #d9a955;
      --gold-soft: #2e2617;
      --good: #6cc492;
      --bad: #e08b83;
      --bad-soft: #33211f;
      --cipher: #6d7f7c;
    }
  }

  * { box-sizing: border-box; }
  body { background: var(--paper); color: var(--ink); font-family: var(--sans); line-height: 1.6; margin: 0; }
  .skip-link { position: absolute; left: -9999px; top: 0; background: var(--teal); color: #fff; padding: 8px 14px; border-radius: 0 0 8px 0; z-index: 10; }
  .skip-link:focus { left: 0; }

  .topbar { border-bottom: 1px solid var(--line); }
  .topbar .inner { max-width: 880px; margin: 0 auto; padding: 14px 22px; display: flex; align-items: center; gap: 10px; }
  .topbar a.brand { display: inline-flex; align-items: center; gap: 10px; color: var(--ink); text-decoration: none; font-weight: 700; font-size: 16px; }
  .topbar nav { display: flex; align-items: center; gap: 16px; margin-left: auto; }
  .topbar nav a { color: var(--muted); font-size: 13px; text-decoration: none; }
  .topbar nav a:hover, .topbar nav a:focus-visible { color: var(--teal); }
  @media (max-width: 560px) { .topbar nav a:not(:last-child) { display: none; } }

  .wrap { max-width: 720px; margin: 0 auto; padding: 0 22px 96px; }
  /* Inside the 720px column, .wide breaks out to up to 880px, centered. */
  .wide { --w: min(880px, calc(100vw - 44px)); width: var(--w); margin-left: calc((100% - var(--w)) / 2); }

  .eyebrow {
    font-size: 12px; letter-spacing: 0.14em; text-transform: uppercase;
    color: var(--teal); font-weight: 600; margin: 56px 0 14px;
  }
  h1 {
    font-family: var(--serif); font-weight: 600; font-size: clamp(30px, 5.5vw, 44px);
    line-height: 1.15; margin: 0 0 18px; text-wrap: balance; letter-spacing: -0.01em;
  }
  .lede { font-size: 18.5px; color: var(--muted); margin: 0 0 8px; max-width: 60ch; }
  h2 {
    font-family: var(--serif); font-weight: 600; font-size: 26px; line-height: 1.25;
    margin: 64px 0 12px; text-wrap: balance;
  }
  h3 { font-size: 16px; font-weight: 650; margin: 28px 0 8px; }
  p { margin: 0 0 16px; max-width: 66ch; }
  .muted { color: var(--muted); }
  .accounting-note { font-size: 14px; margin-top: 14px; }
  .inline-link { color: var(--teal); }
  strong { font-weight: 650; }
  code { font-family: var(--mono); font-size: 0.86em; background: var(--teal-soft); border-radius: 4px; padding: 1px 5px; }

  .keyfact {
    border: 1px solid var(--line); border-left: 3px solid var(--teal);
    background: var(--card); border-radius: 8px; padding: 18px 20px; margin: 28px 0;
    font-size: 16.5px;
  }
  .keyfact b { color: var(--teal); }

  .videobox { margin: 34px 0 8px; }
  .videobox video { width: 100%; border-radius: 12px; border: 1px solid var(--line); display: block; background: #101716; }
  .videobox p { font-size: 13px; color: var(--muted); margin: 10px 0 0; }
  .transcript { border-top: 1px solid var(--line); margin-top: 12px; }
  .transcript summary { color: var(--teal); cursor: pointer; font-size: 14px; font-weight: 650; padding: 12px 0 4px; }
  .transcript div { color: var(--muted); font-size: 14px; padding-top: 8px; }

  figure { margin: 30px 0 8px; }
  .diagram-svg { min-width: 680px; width: 100%; height: auto; }
  .panel {
    background: var(--card); border: 1px solid var(--line); border-radius: 10px;
    padding: 20px; overflow-x: auto;
  }
  figcaption { font-size: 13px; color: var(--muted); margin-top: 10px; line-height: 1.5; max-width: 70ch; }
  svg { display: block; }
  svg text { font-family: var(--sans); }
  svg .m { font-family: var(--mono); }

  .cols { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin-top: 26px; margin-bottom: 6px; }
  @media (max-width: 640px) { .cols { grid-template-columns: 1fr; } }
  .col { border: 1px solid var(--line); border-radius: 10px; background: var(--card); padding: 18px 20px 12px; }
  .col h3 { margin: 0 0 4px; display: flex; align-items: center; gap: 8px; font-size: 15px; }
  .col p.sub { font-size: 13px; color: var(--muted); margin-bottom: 12px; }
  .col ul { list-style: none; margin: 0; padding: 0; }
  .col li { display: flex; gap: 10px; align-items: baseline; padding: 8px 0; border-top: 1px solid var(--line); font-size: 14.5px; }
  .col li .why { display: block; font-size: 12.5px; color: var(--muted); margin-top: 1px; }
  .tick { color: var(--good); font-weight: 700; flex: 0 0 auto; }
  .cross { color: var(--bad); font-weight: 700; flex: 0 0 auto; }
  .badge-good { background: var(--teal-soft); color: var(--teal); border-radius: 99px; font-size: 11px; letter-spacing: 0.08em; text-transform: uppercase; padding: 3px 10px; font-weight: 700; }
  .badge-bad { background: var(--bad-soft); color: var(--bad); border-radius: 99px; font-size: 11px; letter-spacing: 0.08em; text-transform: uppercase; padding: 3px 10px; font-weight: 700; }

  .wire { font-family: var(--mono); font-size: 12.5px; line-height: 1.7; white-space: pre; overflow-x: auto; margin: 0; }
  .wire .k { color: var(--teal); }
  .wire .c { color: var(--cipher); }
  .wire .g { color: var(--gold); }
  .wire .plain { color: var(--ink); }
  .wirelabel { font-size: 11px; letter-spacing: 0.12em; text-transform: uppercase; font-weight: 700; color: var(--muted); margin: 0 0 10px; }

  .faq { margin: 8px 0 0; }
  .faq details { border-top: 1px solid var(--line); padding: 4px 0; }
  .faq details:last-child { border-bottom: 1px solid var(--line); }
  .faq summary { cursor: pointer; font-weight: 600; padding: 12px 0; list-style: none; display: flex; justify-content: space-between; gap: 12px; }
  .faq summary::-webkit-details-marker { display: none; }
  .faq summary::after { content: "+"; color: var(--teal); font-weight: 600; }
  .faq details[open] summary::after { content: "\2013"; }
  .faq summary:focus-visible { outline: 2px solid var(--teal); outline-offset: 2px; border-radius: 4px; }
  .faq .a { padding: 0 0 16px; color: var(--muted); max-width: 66ch; }

  .technote { border: 1px solid var(--line); background: var(--card); border-radius: 10px; padding: 20px 22px; margin: 28px 0; }
  .technote h3 { margin-top: 0; }
  .technote dl { margin: 0; display: grid; grid-template-columns: max-content 1fr; gap: 8px 18px; font-size: 14px; }
  .technote dt { font-family: var(--mono); font-size: 12.5px; color: var(--teal); }
  .technote dd { margin: 0; color: var(--muted); }
  .technical-fixture-note { margin: 16px 0 0; font-size: 14px; }
  @media (max-width: 560px) { .technote dl { grid-template-columns: 1fr; gap: 2px; } .technote dd { margin-bottom: 10px; } }

  .foot { border-top: 1px solid var(--line); margin-top: 72px; padding-top: 18px; font-size: 13px; color: var(--muted); }