:root {
  --bg: #f7f3ec;
  --surface: #ffffff;
  --surface-2: #efe8dc;
  --field-bg: #ffffff;
  --text: #241e18;
  --muted: #5c5145;
  --line: #ddd3c4;
  --field-line: #8a7b6a; /* field borders are at least 3:1 against the background */
  --accent: #8c3f12;
  --accent-ink: #ffffff;
  --accent-soft: #f6e6d8;
  --warn: #8a4b00;
  --warn-soft: #fcf1dc;
  --error: #b3261e;
  --radius: 12px;
  --tap: 44px;
  --shadow: 0 1px 2px rgb(60 40 20 / 0.06), 0 2px 8px rgb(60 40 20 / 0.05);
  --font: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #16120f;
    --surface: #201a16;
    --surface-2: #2a231d;
    --field-bg: #2a231d;
    --text: #f0e9df;
    --muted: #b8ab9c;
    --line: #3a3129;
    --field-line: #857665;
    --accent: #e8a06b;
    --accent-ink: #1a0f08;
    --accent-soft: #3a281b;
    --warn: #f0b44c;
    --warn-soft: #33280f;
    --error: #ff8a80;
    --shadow: none;
    color-scheme: dark;
  }
}

*, *::before, *::after { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.6;
  overflow-wrap: break-word;
}

h1, h2, h3 { text-wrap: balance; }
.lead { text-wrap: pretty; }

a { color: var(--accent); }
a:hover { text-decoration-thickness: 2px; }

.wrap { max-width: 760px; margin: 0 auto; padding: 0 16px; }

.skip-link { position: absolute; left: 8px; top: -60px; z-index: 10; background: var(--accent); color: var(--accent-ink); padding: 10px 14px; border-radius: 8px; font-weight: 700; text-decoration: none; }
.skip-link:focus { top: 8px; }
main:focus { outline: none; }

/* Header */
.site-header { background: var(--surface); border-bottom: 1px solid var(--line); }
.site-header > .wrap { display: flex; align-items: center; min-height: 56px; }
.logo { display: inline-flex; align-items: center; gap: 8px; min-height: var(--tap); color: var(--text); text-decoration: none; font-weight: 700; font-size: 1.2rem; letter-spacing: -0.01em; }
.logo svg { color: var(--accent); }
.site-nav { border-top: 1px solid var(--line); }
.site-nav .wrap { display: flex; gap: 4px; overflow-x: auto; padding-top: 4px; padding-bottom: 4px; scrollbar-width: none; }
.site-nav .wrap::-webkit-scrollbar { display: none; }
.site-nav a { flex: none; display: inline-flex; align-items: center; min-height: var(--tap); padding: 0 12px; border-radius: 999px; color: var(--muted); text-decoration: none; font-size: 0.92rem; white-space: nowrap; }
.site-nav a:hover { background: var(--surface-2); color: var(--text); }
.site-nav a[aria-current="page"] { background: var(--accent-soft); color: var(--accent); font-weight: 700; }

/* Content */
main { padding-bottom: 48px; }
.crumbs { margin-top: 4px; font-size: 0.85rem; color: var(--muted); display: flex; flex-wrap: wrap; align-items: center; gap: 0 6px; }
.crumbs a { color: var(--muted); display: inline-flex; align-items: center; min-height: var(--tap); min-width: var(--tap); }
h1 { font-size: 1.75rem; line-height: 1.25; margin: 16px 0 8px; letter-spacing: -0.01em; }
.lead { color: var(--muted); font-size: 1.05rem; margin: 0 0 20px; }
h2 { font-size: 1.35rem; line-height: 1.3; margin: 40px 0 12px; padding-bottom: 6px; border-bottom: 2px solid var(--line); }
h3 { font-size: 1.08rem; line-height: 1.35; margin: 28px 0 8px; }
p, ul, ol { margin: 0 0 14px; }
li { margin-bottom: 4px; }
code { font-family: var(--mono); font-size: 0.92em; background: var(--surface-2); padding: 1px 5px; border-radius: 4px; }
.formula { background: var(--surface); border: 1px solid var(--line); border-left: 4px solid var(--accent); border-radius: 6px; padding: 10px 14px; margin: 0 0 14px; font-variant-numeric: tabular-nums; }
.formula strong { display: block; margin-bottom: 2px; }
.example { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 12px 16px; margin: 0 0 16px; }
.example > :last-child { margin-bottom: 0; }
.example h3 { margin-top: 0; }
.note { font-size: 0.88rem; color: var(--muted); }
.meta { font-size: 0.85rem; color: var(--muted); margin-top: 32px; }
.callout { background: var(--warn-soft); border-left: 4px solid var(--warn); padding: 10px 14px; border-radius: 6px; font-size: 0.95rem; margin: 16px 0; }
.sources ul { font-size: 0.92rem; padding-left: 20px; }
.contact-mail { font-size: 1.2rem; font-weight: 700; }

.mt-m { margin-top: 12px; }

table { width: 100%; border-collapse: collapse; margin: 0 0 8px; font-size: 0.95rem; }
caption { text-align: left; font-weight: 700; padding: 0 0 6px; }
th, td { border: 1px solid var(--line); padding: 6px 10px; text-align: left; vertical-align: top; background: var(--surface); }
th { background: var(--surface-2); font-weight: 600; }
td.num, th.num { text-align: right; font-variant-numeric: tabular-nums; }
td.num { white-space: nowrap; }
.table-scroll { overflow-x: auto; margin-bottom: 16px; }
.table-scroll:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.table-scroll table { margin: 0; }
td a, th a { display: inline-flex; align-items: center; min-height: var(--tap); min-width: var(--tap); }
.table-note { font-size: 0.85rem; color: var(--muted); margin: -8px 0 16px; }

/* Calculator card */
.tool { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); padding: 16px; margin: 0 0 20px; }
.tool > h2:first-child { margin-top: 0; font-size: 1.15rem; border: 0; padding: 0; }
.tool-hint { font-size: 0.88rem; color: var(--muted); margin: 4px 0 12px; }
.tool-hint.mt-m { margin: 12px 0 8px; }
.tool-sub { font-size: 1rem; margin: 20px 0 8px; }

label { font-size: 0.9rem; color: var(--muted); }
input[type="text"], select {
  font: inherit;
  font-size: 1.1rem;
  color: var(--text);
  background: var(--field-bg);
  border: 1px solid var(--field-line);
  border-radius: 8px;
  padding: 8px 10px;
  min-height: var(--tap);
  width: 100%;
  font-variant-numeric: tabular-nums;
}
input::placeholder { color: var(--muted); opacity: 0.9; }
input:focus-visible, select:focus-visible, button:focus-visible, summary:focus-visible, a:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
input[aria-invalid="true"] { border-color: var(--error); box-shadow: 0 0 0 1px var(--error); }
.field { display: flex; flex-direction: column; gap: 2px; min-width: 0; }
.unit-input { display: flex; align-items: center; gap: 6px; }
.unit-input input { text-align: right; min-width: 0; }
.unit-input span { flex: none; color: var(--muted); }
.unit-select { width: auto; flex: none; max-width: 45%; font-size: 1rem; }
.stack { display: flex; flex-direction: column; gap: 12px; }
.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; align-items: end; }
.opts { margin-top: 4px; }
.opts + .opts { margin-top: 12px; }
[hidden] { display: none !important; }

/* Area cards */
.area { border: 1px solid var(--line); border-radius: 10px; margin: 0 0 12px; padding: 4px 12px 12px; background: var(--surface); min-width: 0; }
.area legend { padding: 0 6px; font-weight: 700; color: var(--text); }
.area .field { margin-top: 8px; }
.dims { display: grid; grid-template-columns: 1fr; gap: 0 16px; }
.depth-row { display: grid; grid-template-columns: 1fr; gap: 0 16px; }
@media (min-width: 560px) {
  .dims:has(> .field + .field) { grid-template-columns: 1fr 1fr; }
  .depth-row { grid-template-columns: 3fr 2fr; }
}
.depth-row .field > input { text-align: right; } /* the Quantity box lines up with the other numbers */
.btn-quiet { margin-top: 12px; }

.btn {
  font: inherit;
  font-size: 0.95rem;
  border-radius: 8px;
  border: 1px solid var(--field-line);
  background: var(--surface);
  color: var(--text);
  padding: 8px 14px;
  min-height: var(--tap);
  cursor: pointer;
}
.btn:hover { background: var(--surface-2); }
.btn-row { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 4px; }

/* Result */
.result { margin-top: 20px; background: var(--accent-soft); border-radius: 10px; padding: 14px 16px; }
.result:empty { min-height: 72px; }
.result-main { font-size: 2.1rem; font-weight: 700; line-height: 1.2; font-variant-numeric: tabular-nums; color: var(--text); }
.result-main small { display: block; font-size: 1.05rem; font-weight: 600; color: var(--muted); margin-top: 2px; }
.result dl { display: grid; grid-template-columns: fit-content(45%) minmax(0, 1fr); gap: 6px 14px; margin: 12px 0 0; padding-top: 12px; border-top: 1px solid color-mix(in srgb, var(--accent) 30%, transparent); font-size: 0.95rem; }
.result dt { color: var(--muted); }
.result dd { margin: 0; font-variant-numeric: tabular-nums; font-weight: 600; min-width: 0; }
.result dd small { display: block; font-weight: 400; font-size: 0.84rem; color: var(--muted); }
.result .err { color: var(--error); font-weight: 600; font-size: 1rem; }
.result-empty { margin: 0; color: var(--muted); }
.result-notice { margin: 12px 0 0; font-size: 0.9rem; color: var(--warn); font-weight: 600; }
.result-actions { display: flex; justify-content: flex-end; margin-top: 10px; }
.copy-btn { font-size: 0.9rem; }

/* "Next step" card after the calculator: quiet, one outlined button, nothing that looks like an advert */
.next-step { background: var(--surface); border: 1px solid var(--line); border-left: 4px solid var(--accent); border-radius: var(--radius); padding: 12px 16px 14px; margin: 0 0 24px; }
.next-step p { margin: 0; }
.next-step-label { font-size: 0.78rem; font-weight: 700; letter-spacing: 0.06em; text-transform: uppercase; color: var(--muted); }
.next-step-title { margin-top: 2px; font-weight: 700; }
.next-step-text { margin: 2px 0 10px; font-size: 0.95rem; color: var(--muted); }
.next-step .btn { display: inline-flex; align-items: center; text-decoration: none; font-weight: 600; color: var(--accent); border-color: var(--accent); }

/* Lists of calculators and the FAQ */
.tool-list { list-style: none; padding: 0; display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 10px; }
.tool-list li { margin: 0; }
.tool-list a { display: block; height: 100%; padding: 12px 14px; background: var(--surface); border: 1px solid var(--line); border-radius: 10px; text-decoration: none; color: var(--text); }
.tool-list a:hover { border-color: var(--accent); }
.tool-list strong { display: block; color: var(--accent); }
.tool-list span { display: block; font-size: 0.88rem; color: var(--muted); line-height: 1.5; }
.faq details { border: 1px solid var(--line); border-radius: 10px; background: var(--surface); margin-bottom: 8px; }
.faq summary { cursor: pointer; padding: 10px 14px; min-height: var(--tap); font-weight: 600; display: flex; align-items: center; }
.faq details > div { padding: 0 14px 4px; }
.faq details > div > :last-child { margin-bottom: 10px; }

.site-footer { border-top: 1px solid var(--line); background: var(--surface); padding: 20px 0 28px; font-size: 0.88rem; color: var(--muted); }
.site-footer p { margin: 0 0 6px; }
.site-footer a { color: var(--muted); }
.footer-links { display: flex; flex-wrap: wrap; gap: 0 20px; }
.footer-links a { display: inline-flex; align-items: center; justify-content: center; min-height: var(--tap); min-width: var(--tap); }

@media (max-width: 480px) {
  h1 { font-size: 1.5rem; }
  .result-main { font-size: 1.9rem; }
  .tool { padding: 12px; }
  table { font-size: 0.875rem; }
  th, td { padding: 6px 7px; }
}

/* On phones and short screens, keep the main figure in view while a field is being edited. The breakdown
   folds away while typing so the result bar stays small. Browsers without :has() just
   show the whole result in the normal flow. */
@media (max-width: 600px), (max-height: 1000px) {
  html:has(.tool input:focus, .tool select:focus) { scroll-padding-bottom: 9rem; } /* a field reached with Tab is never left under the bar */
  .tool:has(input:focus, select:focus) .result { position: sticky; bottom: 0; z-index: 2; box-shadow: 0 -4px 12px rgb(0 0 0 / 0.18); }
  .tool:has(input:focus, select:focus) .result dl,
  .tool:has(input:focus, select:focus) .result-notice { display: none; }
  /* The Copy button is hidden by clipping, not by display: none, so Tab from the last field still reaches it
     (the bar opens up again as soon as it has focus). */
  .tool:has(input:focus, select:focus) .result-actions { position: absolute; width: 1px; height: 1px; margin: 0; overflow: hidden; clip: rect(0 0 0 0); }
}

@media (prefers-reduced-motion: reduce) {
  * { scroll-behavior: auto !important; transition: none !important; animation: none !important; }
}

@media print {
  .site-header, .site-nav, .related, .site-footer, .btn-row, .result-actions, .skip-link, .next-step { display: none !important; }
  body { background: #fff; color: #000; }
}

.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0; }