:root {
  --bg: #f6f7f5;
  --panel: #ffffff;
  --ink: #142028;
  --ink-2: #4a5963;
  --line: #dde3e1;
  --accent: #0b5f75;
  --accent-ink: #ffffff;
  --accent-soft: #e2f0f3;
  --clear: #1c7a45;
  --clear-soft: #e3f3e9;
  --marginal: #a15c07;
  --marginal-soft: #fbefdc;
  --none: #a8322d;
  --none-soft: #f8e4e2;
  --noise: rgba(11, 95, 117, 0.12);
  --host: #efe9df;
  --body: #0b5f75;
  --radius: 10px;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0f1518;
    --panel: #172025;
    --ink: #e6ecee;
    --ink-2: #9fb0b8;
    --line: #2a363c;
    --accent: #5cc3dc;
    --accent-ink: #0f1518;
    --accent-soft: #163640;
    --clear: #5fd08f;
    --clear-soft: #173326;
    --marginal: #f0b25a;
    --marginal-soft: #3a2a12;
    --none: #f08a84;
    --none-soft: #3b1d1b;
    --noise: rgba(92, 195, 220, 0.16);
    --host: #2a2620;
    --body: #5cc3dc;
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scrollbar-gutter: stable; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 16px/1.55 var(--sans);
}
a { color: var(--accent); }
h1, h2, h3 { line-height: 1.2; margin: 0 0 0.5em; }
p { margin: 0 0 0.8em; }
.wrap { width: 100%; max-width: 1320px; margin: 0 auto; padding: 0 24px; }
.muted { color: var(--ink-2); }

/* header and footer */
.site-header { border-bottom: 1px solid var(--line); background: var(--panel); }
.header-row { display: flex; align-items: center; justify-content: space-between; gap: 16px; min-height: 60px; }
.brand { display: flex; align-items: center; gap: 10px; color: var(--ink); text-decoration: none; font-weight: 700; font-size: 1.15rem; }
.mark { width: 30px; height: 30px; display: block; }
.nav { display: flex; gap: 4px; flex-wrap: wrap; }
.nav a { color: var(--ink-2); text-decoration: none; padding: 6px 12px; border-radius: 8px; }
.nav a:hover { background: var(--accent-soft); color: var(--ink); }
.nav a[aria-current="page"] { color: var(--ink); font-weight: 600; }
.site-footer { border-top: 1px solid var(--line); margin-top: 56px; padding: 22px 0 32px; font-size: 0.9rem; }
.footer-row p { margin: 0 0 4px; }

/* hero */
.hero { padding-top: 36px; padding-bottom: 8px; }
.hero h1 { font-size: clamp(1.9rem, 3.4vw, 2.7rem); letter-spacing: -0.01em; margin-bottom: 4px; }
.tagline { font-size: clamp(1.15rem, 1.8vw, 1.4rem); color: var(--accent); font-weight: 600; margin-bottom: 12px; }
.lead { font-size: 1.1rem; color: var(--ink-2); max-width: none; }
.examples { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 14px; }
.chip {
  border: 1px solid var(--line); background: var(--panel); color: var(--ink);
  border-radius: 999px; padding: 6px 14px; font: inherit; font-size: 0.92rem; cursor: pointer;
}
.chip:hover { border-color: var(--accent); color: var(--accent); }

/* tool layout */
.tool { display: grid; grid-template-columns: minmax(340px, 420px) 1fr; gap: 24px; align-items: start; margin-top: 24px; }
.panel { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 20px; }
.form { position: sticky; top: 16px; max-height: calc(100vh - 32px); overflow: auto; }
fieldset { border: 0; padding: 0; margin: 0 0 18px; min-width: 0; }
legend { font-weight: 700; font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.06em; color: var(--ink-2); margin-bottom: 10px; padding: 0; }
label { display: block; font-size: 0.88rem; color: var(--ink-2); }
label > input, label > select { display: block; margin-top: 4px; }
label[hidden] { display: none; }
.unit { color: var(--ink-2); font-size: 0.8rem; }
input, select {
  font: inherit; font-size: 0.95rem; color: var(--ink); background: var(--bg);
  border: 1px solid var(--line); border-radius: 8px; padding: 8px 10px; width: 100%; min-width: 0;
}
input:focus, select:focus, button:focus-visible { outline: 2px solid var(--accent); outline-offset: 1px; }
.grid2 { display: grid; grid-template-columns: 1fr 1fr; gap: 10px 12px; margin-bottom: 10px; }
.grid3 { display: grid; grid-template-columns: 1fr 1fr 1.2fr; gap: 10px 12px; margin-bottom: 6px; }
.hint { font-size: 0.82rem; color: var(--ink-2); margin: 2px 0 10px; }
.checks { display: flex; gap: 18px; }
.check { display: flex; align-items: center; gap: 8px; font-size: 0.95rem; color: var(--ink); }
.check input { width: auto; margin: 0; }
.shapes { display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px; margin-bottom: 6px; }
.shape {
  display: flex; flex-direction: column; align-items: center; gap: 4px; padding: 8px 4px;
  border: 1px solid var(--line); border-radius: 8px; background: var(--bg); color: var(--ink);
  font: inherit; font-size: 0.8rem; cursor: pointer;
}
.shape svg { width: 40px; height: 36px; fill: none; stroke: var(--ink-2); stroke-width: 1.6; }
.shape[aria-checked="true"] { border-color: var(--accent); background: var(--accent-soft); }
.shape[aria-checked="true"] svg { stroke: var(--accent); }
.shape[aria-checked="true"] svg :not(path:first-child) { fill: var(--accent); fill-opacity: 0.25; }
.link-btn { background: none; border: 0; color: var(--accent); font: inherit; font-size: 0.88rem; padding: 0; cursor: pointer; text-decoration: underline; }
.locate-row .link-btn { margin-right: 6px; }
.more { margin-top: 12px; }
.more summary { cursor: pointer; font-size: 0.9rem; color: var(--accent); margin-bottom: 10px; }
.error { color: var(--none); background: var(--none-soft); border-radius: 8px; padding: 8px 12px; font-size: 0.9rem; }

/* results */
.results { display: flex; flex-direction: column; gap: 16px; min-width: 0; }
.placeholder { color: var(--ink-2); }
.verdict-head { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 12px 24px; }
.verdict-head .kicker { margin: 0; font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.06em; color: var(--ink-2); flex-basis: 100%; }
.verdict-head .big { margin: -6px 0 0; font-size: 1.6rem; font-weight: 700; color: var(--clear); }
.verdict-head.is-none .big { color: var(--none); }
.actions { display: flex; flex-wrap: wrap; gap: 8px; }
.btn {
  font: inherit; font-size: 0.9rem; padding: 8px 14px; border-radius: 8px; cursor: pointer;
  border: 1px solid var(--accent); background: var(--accent); color: var(--accent-ink);
}
.btn + .btn { background: transparent; color: var(--accent); }
.method-title { display: flex; align-items: center; gap: 12px; margin-bottom: 12px; }
.method-title h2 { margin: 0; font-size: 1.3rem; }
.badge { border-radius: 999px; padding: 3px 12px; font-size: 0.85rem; font-weight: 600; }
.badge.clear { background: var(--clear-soft); color: var(--clear); }
.badge.marginal { background: var(--marginal-soft); color: var(--marginal); }
.badge.none { background: var(--none-soft); color: var(--none); }
.muted-badge { background: var(--bg); color: var(--ink-2); }
.metrics { display: grid; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); gap: 10px; margin: 0 0 14px; }
.metrics div { background: var(--bg); border-radius: 8px; padding: 10px 12px; }
.metrics dt { font-size: 0.78rem; color: var(--ink-2); }
.metrics dd { margin: 2px 0 0; font: 600 1.15rem/1.3 var(--mono); }
.figure { margin: 0 0 10px; }
/* charts are server-drawn images, one per colour theme */
.chart { display: block; width: 100%; height: auto; }
.chart-dark { display: none; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .chart-light { display: none; }
  :root:not([data-theme="light"]) .chart-dark { display: block; }
}
figcaption { font-size: 0.85rem; margin-top: 6px; }
.facts { font-size: 0.88rem; color: var(--ink-2); }
.assumptions summary { cursor: pointer; color: var(--accent); font-size: 0.9rem; }
.assumptions ul { margin: 8px 0 0; padding-left: 20px; font-size: 0.88rem; color: var(--ink-2); }

/* text pages */
.prose { padding-top: 32px; }
.prose h1 { font-size: 2rem; }
.prose h2 { font-size: 1.3rem; margin-top: 1.6em; }
.prose table { border-collapse: collapse; width: 100%; font-size: 0.92rem; margin: 0 0 1em; }
.prose th, .prose td { text-align: left; border-bottom: 1px solid var(--line); padding: 8px 10px 8px 0; vertical-align: top; }
.prose code, .prose pre { font-family: var(--mono); font-size: 0.88rem; }
.prose pre { background: var(--panel); border: 1px solid var(--line); border-radius: 8px; padding: 12px 14px; overflow-x: auto; white-space: pre-wrap; overflow-wrap: anywhere; }
.cols { display: grid; grid-template-columns: 1fr 1fr; gap: 0 40px; }
.cols > * { min-width: 0; }
.prose td.num, .prose th.num { text-align: right; font-family: var(--mono); white-space: nowrap; }
.prose th.num { font-family: inherit; white-space: normal; }
.table-wrap { overflow-x: auto; }
.case { margin-top: 2em; }
.case h2 { margin-top: 0; }
.key { display: inline-block; width: 22px; height: 0; vertical-align: middle; margin-right: 6px; }
.key-model { border-top: 2.4px solid var(--accent); }
.key-ref { width: 10px; height: 10px; border: 1.8px solid #b45f06; border-radius: 50%; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .key-ref { border-color: #f0b25a; } }
.case .figure { max-width: 880px; }
.prose { overflow-wrap: break-word; }

@media (max-width: 960px) {
  .tool { grid-template-columns: 1fr; }
  .form { position: static; max-height: none; }
  .cols { grid-template-columns: 1fr; }
}
@media (max-width: 640px) {
  /* logo on the first line, the menu on one line under it */
  .header-row { flex-wrap: wrap; gap: 2px; padding-top: 10px; padding-bottom: 6px; }
  .nav { flex-wrap: nowrap; width: 100%; justify-content: space-between; gap: 0; margin: 0 -7px; }
  .nav a { padding: 4px 7px; font-size: 0.92rem; }
  /* the summary keeps the case and its error; the methods are described under each figure */
  .summary th:nth-child(1), .summary td:nth-child(1), .summary th:nth-child(3), .summary td:nth-child(3) { display: none; }
  .summary td.num { font-size: 0.8rem; }
  .summary th, .summary td { padding-right: 6px; }
}
@media (max-width: 520px) {
  .wrap { padding: 0 16px; }
  .grid3 { grid-template-columns: 1fr 1fr; }
  .grid3 label:last-child { grid-column: span 2; }
  .panel { padding: 16px; }
  .brand { font-size: 1.05rem; gap: 8px; }
  .mark { width: 26px; height: 26px; }
}