:root {
  color-scheme: light dark;
  --bg: #f2f6f9;
  --panel: #ffffff;
  --ink: #16202a;
  --muted: #4c5b69;
  --line: #c3cedA;
  --wire: #d5dee7;
  --leaf: #2e6b45;
  --glow: #b0166f;
  --glow-soft: rgba(176, 22, 111, 0.16);
  --on-glow: #ffffff;
  --peat: #5a4333;
  --focus: #0b5fff;
  --sans: "Helvetica Neue", Helvetica, Arial, "Segoe UI", sans-serif;
  --serif: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, serif;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f161c;
    --panel: #17212a;
    --ink: #e8eef3;
    --muted: #a5b3c0;
    --line: #33424f;
    --wire: #243340;
    --leaf: #7cc795;
    --glow: #ff5db1;
    --glow-soft: rgba(255, 93, 177, 0.2);
    --on-glow: #16202a;
    --peat: #8a6a52;
    --focus: #7aa7ff;
  }
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 18px/1.65 var(--serif);
}
a { color: var(--glow); text-underline-offset: 3px; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 3px solid var(--focus); outline-offset: 3px; border-radius: 2px; }

.skip { position: absolute; left: -999px; top: 0; background: var(--ink); color: var(--bg); padding: 10px 14px; z-index: 10; }
.skip:focus { left: 8px; top: 8px; }

.wrap { width: min(1080px, 100% - 40px); margin-inline: auto; }

/* header */
.site-head { border-bottom: 1px solid var(--line); background: var(--panel); }
.site-head .wrap { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 8px 24px; padding-block: 14px; }
.brand { font: 800 20px/1 var(--sans); letter-spacing: -0.02em; color: var(--ink); text-decoration: none; display: inline-flex; align-items: center; gap: 10px; }
.brand-mark { width: 26px; height: 8px; border-radius: 4px; background: var(--glow); box-shadow: 0 0 0 5px var(--glow-soft); }
.site-head nav { display: flex; flex-wrap: wrap; gap: 4px 22px; font: 600 15px/1 var(--sans); }
.site-head nav a { color: var(--ink); text-decoration: none; padding: 8px 0; border-bottom: 2px solid transparent; }
.site-head nav a:hover, .site-head nav a[aria-current="page"] { border-bottom-color: var(--glow); }

/* type */
h1, h2, h3 { font-family: var(--sans); letter-spacing: -0.02em; line-height: 1.12; margin: 0 0 0.5em; }
h1 { font-size: clamp(34px, 5.2vw, 58px); font-weight: 800; }
h2 { font-size: clamp(25px, 3vw, 32px); font-weight: 800; margin-top: 2.2em; }
h3 { font-size: 20px; font-weight: 700; margin-top: 1.8em; }
p, ul, ol { margin: 0 0 1.1em; }
.prose { max-width: 68ch; }
.lede { font-size: 21px; color: var(--muted); max-width: 60ch; }
.meta { font: 14px/1.5 var(--sans); color: var(--muted); }
small, .small { font: 14px/1.5 var(--sans); color: var(--muted); }

/* hero */
.hero { padding-block: clamp(36px, 7vw, 84px); }
.hero .wrap { display: grid; grid-template-columns: 1.05fr 0.95fr; gap: clamp(24px, 5vw, 64px); align-items: center; }
.hero-art { background: var(--panel); border: 1px solid var(--line); border-radius: 10px; padding: 14px 14px 10px; }
.hero-art figcaption { font: 14px/1.5 var(--sans); color: var(--muted); padding: 8px 4px 2px; }
.actions { display: flex; flex-wrap: wrap; gap: 14px 22px; align-items: center; margin-top: 28px; }
.btn { display: inline-block; background: var(--glow); color: var(--on-glow); font: 700 17px/1 var(--sans); padding: 15px 22px; border-radius: 6px; text-decoration: none; border: 0; cursor: pointer; }
.btn:hover { filter: brightness(1.08); }
.btn.quiet { background: transparent; color: var(--ink); border: 1px solid var(--line); }
.textlink { font: 600 16px/1.2 var(--sans); }

/* diagram */
.diagram svg { width: 100%; height: auto; display: block; }
.d-shelf { fill: var(--panel); stroke: var(--ink); stroke-width: 2; }
.d-wire { stroke: var(--wire); stroke-width: 1; fill: none; }
.d-tray { fill: var(--peat); stroke: var(--ink); stroke-opacity: 0.45; stroke-width: 1; }
.d-glow { fill: var(--glow-soft); }
.d-bar { fill: var(--glow); }
.d-dim { font: 600 13px var(--sans); fill: var(--muted); }

/* sections */
.band { padding-block: clamp(28px, 5vw, 56px); border-top: 1px solid var(--line); }
.band h2:first-child { margin-top: 0; }
table { border-collapse: collapse; width: 100%; font: 16px/1.5 var(--sans); background: var(--panel); border: 1px solid var(--line); }
th, td { text-align: left; padding: 12px 14px; vertical-align: top; border-bottom: 1px solid var(--line); }
th { font-weight: 700; background: color-mix(in srgb, var(--panel) 90%, var(--ink)); }
td:first-child { font-weight: 700; white-space: nowrap; }
.table-scroll { overflow-x: auto; }
.callout { border-left: 4px solid var(--glow); padding: 4px 0 4px 18px; margin: 1.4em 0; }
.callout p:last-child { margin-bottom: 0; }
.sources li { margin-bottom: 0.6em; font-size: 16px; }
.todo { background: #fff3a8; color: #3b3200; padding: 0 4px; border-radius: 3px; font-family: var(--sans); font-size: 0.9em; }

/* breadcrumbs */
.crumbs { font: 14px/1.4 var(--sans); color: var(--muted); padding-top: 22px; }
.crumbs a { color: var(--muted); }

/* calculator */
.calc { display: grid; grid-template-columns: minmax(280px, 400px) 1fr; gap: clamp(20px, 4vw, 48px); align-items: start; margin-block: 28px 8px; }
.calc form { background: var(--panel); border: 1px solid var(--line); border-radius: 10px; padding: 8px 20px 20px; font-family: var(--sans); }
fieldset { border: 0; border-top: 1px solid var(--line); margin: 14px 0 0; padding: 14px 0 0; min-width: 0; }
fieldset:first-of-type { border-top: 0; margin-top: 8px; }
legend { font: 800 17px/1.2 var(--sans); padding: 0; margin-bottom: 10px; }
.field { margin-bottom: 12px; }
.field label { display: block; font: 600 14px/1.3 var(--sans); margin-bottom: 4px; }
.field .hint { font: 13px/1.4 var(--sans); color: var(--muted); margin-top: 3px; }
.field input, .field select { width: 100%; font: 16px var(--sans); padding: 10px 11px; border: 1px solid var(--line); border-radius: 6px; background: var(--bg); color: var(--ink); }
.pair { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.results { position: sticky; top: 16px; }
.stats { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 0; border: 1px solid var(--line); background: var(--panel); border-radius: 10px; margin: 18px 0; overflow: hidden; font-family: var(--sans); }
.stat { padding: 14px 16px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); margin: 0 -1px -1px 0; }
.stat dt { font: 600 13px/1.3 var(--sans); color: var(--muted); margin: 0 0 4px; }
.stat dd { margin: 0; font: 800 30px/1.1 var(--sans); letter-spacing: -0.02em; }
.stat dd small { display: block; font: 13px/1.4 var(--sans); color: var(--muted); font-weight: 400; letter-spacing: 0; margin-top: 4px; }
#r-notes { font: 15px/1.5 var(--sans); padding-left: 20px; }
#r-notes li { margin-bottom: 8px; }

/* footer */
.site-foot { border-top: 1px solid var(--line); margin-top: 64px; padding-block: 28px 40px; font: 15px/1.6 var(--sans); color: var(--muted); }
.site-foot .wrap { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 16px 40px; }
.site-foot nav { display: flex; flex-wrap: wrap; gap: 6px 20px; }
.site-foot a { color: var(--muted); }

@media (max-width: 820px) {
  body { font-size: 17px; }
  .hero .wrap, .calc { grid-template-columns: 1fr; }
  .results { position: static; }
}
@media (prefers-reduced-motion: reduce) { * { scroll-behavior: auto !important; transition: none !important; } }
@media print { .site-head nav, .site-foot nav, .btn { display: none; } body { background: #fff; color: #000; } }