:root {
  --ink: #1c2430;
  --muted: #5b6675;
  --line: #d9dee6;
  --bg: #f7f8fa;
  --card: #ffffff;
  --accent: #0f6b5c;
  --accent-soft: #e3f0ed;
  --warn: #b3541e;
  --warn-soft: #f8ecdf;
  --bad: #a03030;
  --bad-soft: #f5e3e3;
  --good: #2e7d32;
  --good-soft: #e6f2e7;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.55;
}
.nav {
  display: flex; align-items: center; justify-content: space-between;
  max-width: 1080px; margin: 0 auto; padding: 14px 20px;
}
.brand { font-weight: 700; font-size: 1.25rem; color: var(--accent); text-decoration: none; letter-spacing: .02em; }
.nav-links a { margin-left: 18px; color: var(--muted); text-decoration: none; }
.nav-links a:hover { color: var(--ink); }
main { max-width: 1080px; margin: 0 auto; padding: 0 20px 40px; }
.hero { padding: 26px 0 10px; }
.hero h1 { font-size: clamp(1.6rem, 4vw, 2.3rem); margin: 0 0 8px; }
.lede { color: var(--muted); font-size: 1.05rem; max-width: 46rem; margin: 0; }

.tool {
  display: grid; grid-template-columns: minmax(300px, 5fr) minmax(320px, 6fr);
  gap: 20px; margin-top: 22px;
}
@media (max-width: 780px) { .tool { grid-template-columns: 1fr; } }
.panel {
  background: var(--card); border: 1px solid var(--line); border-radius: 12px;
  padding: 20px 22px;
}
.panel h2 { font-size: 1.05rem; margin: 4px 0 12px; text-transform: uppercase; letter-spacing: .06em; color: var(--muted); }
.panel label { display: block; margin: 12px 0 6px; font-weight: 600; font-size: .95rem; }
.row { display: flex; align-items: center; gap: 10px; }
.row input[type="range"] { flex: 1; }
.row output { min-width: 84px; text-align: right; font-variant-numeric: tabular-nums; font-weight: 700; }
.suffix { color: var(--muted); }
input[type="number"] { width: 110px; padding: 6px 8px; border: 1px solid var(--line); border-radius: 6px; font-size: 1rem; }
select { padding: 6px 8px; border: 1px solid var(--line); border-radius: 6px; font-size: 1rem; background: #fff; }
.hint { color: var(--muted); font-size: .85rem; margin: 14px 0 2px; }
.opt { font-weight: 400; color: var(--muted); font-size: .85rem; }
.presets { margin-top: 18px; display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }
.presets-label { font-size: .85rem; color: var(--muted); }
.presets button {
  border: 1px solid var(--accent); color: var(--accent); background: var(--accent-soft);
  border-radius: 999px; padding: 5px 12px; font-size: .85rem; cursor: pointer;
}
.presets button:hover { background: var(--accent); color: #fff; }

.svgwrap { display: flex; justify-content: center; }
#viz { width: 100%; max-width: 420px; height: auto; }
.scalebar { text-align: center; color: var(--muted); font-size: .85rem; margin-top: 2px; }
.verdict { margin-top: 14px; padding: 12px 16px; border-radius: 10px; font-weight: 700; }
.verdict.good { background: var(--good-soft); color: var(--good); }
.verdict.fair { background: var(--warn-soft); color: var(--warn); }
.verdict.bad  { background: var(--bad-soft);  color: var(--bad); }
.verdict .sub { display: block; font-weight: 400; color: var(--ink); font-size: .9rem; margin-top: 4px; }
.readout { margin-top: 12px; font-size: .92rem; }
.readout table { width: 100%; border-collapse: collapse; }
.readout td { padding: 4px 0; border-bottom: 1px solid var(--line); }
.readout td:last-child { text-align: right; font-variant-numeric: tabular-nums; font-weight: 600; }

.explainer { margin-top: 30px; background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 20px 24px; }
.explainer h2 { margin-top: 0; }
.explainer ul { padding-left: 20px; }
.explainer li { margin: 10px 0; }

footer { border-top: 1px solid var(--line); margin-top: 40px; }
footer p { max-width: 1080px; margin: 12px auto; padding: 0 20px; color: var(--muted); font-size: .9rem; }
.fineprint { font-size: .8rem !important; }

/* content pages */
article.page { background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 26px 30px; margin-top: 24px; }
article.page h1 { margin-top: 0; }
article.page h2 { margin-top: 26px; }
table.chart { width: 100%; border-collapse: collapse; margin: 14px 0; font-size: .95rem; }
table.chart th, table.chart td { border: 1px solid var(--line); padding: 7px 10px; text-align: left; }
table.chart th { background: var(--accent-soft); }
table.chart td.num { text-align: right; font-variant-numeric: tabular-nums; }
.callout { background: var(--accent-soft); border-left: 4px solid var(--accent); padding: 10px 16px; border-radius: 0 8px 8px 0; margin: 16px 0; }
/* printable ruler (page A) */
.printruler { position: relative; height: 34mm; margin: 10px 0 4px 8mm; border-bottom: 2px solid #1c2430; }
.printruler .tick { position: absolute; bottom: 0; width: 1px; background: #1c2430; }
.printruler .t1 { width: .35mm; }
.printruler .t5 { width: .5mm; }
.printruler .t10 { width: .7mm; }
.printruler .lbl { position: absolute; top: 0; transform: translateX(-50%); font-size: 9px; font-weight: 600; }
.printnote { font-size: .85rem; color: var(--muted); }
@media print {
  body { background: #fff; }
  .nav, footer, .no-print { display: none !important; }
  article.page { border: 0; padding: 0; }
  .printruler { margin-left: 6mm; }
}