/* Design tokens */
:root {
  --bg: #f6f5f1;
  --surface: #ffffff;
  --surface-2: #eeece6;
  --text: #1c1c1a;
  --muted: #5d5b55;
  --line: #d9d6cd;
  --brand: #1f3a5f;
  --brand-ink: #ffffff;
  --accent: #f28c28;
  --accent-ink: #1c1c1a;
  --ok: #2c7a4b;
  --focus: #f28c28;
  --radius: 10px;
  --shadow: 0 1px 2px rgba(0,0,0,.06), 0 6px 20px rgba(0,0,0,.05);
  --mono: ui-monospace, "Cascadia Mono", "Segoe UI Mono", Menlo, Consolas, monospace;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #14161a; --surface: #1c1f25; --surface-2: #242830; --text: #ecebe6; --muted: #a7a59c;
    --line: #333842; --brand: #2c4f7f; --brand-ink: #ffffff; --accent: #f5a04a; --accent-ink: #14161a;
    --ok: #57b47c; --focus: #f5a04a; --shadow: 0 1px 2px rgba(0,0,0,.4), 0 6px 20px rgba(0,0,0,.35);
  }
}
:root[data-theme="dark"] {
  --bg: #14161a; --surface: #1c1f25; --surface-2: #242830; --text: #ecebe6; --muted: #a7a59c;
  --line: #333842; --brand: #2c4f7f; --brand-ink: #ffffff; --accent: #f5a04a; --accent-ink: #14161a;
  --ok: #57b47c; --focus: #f5a04a; --shadow: 0 1px 2px rgba(0,0,0,.4), 0 6px 20px rgba(0,0,0,.35);
}

*, *::before, *::after { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--bg); color: var(--text); font-family: var(--sans);
  font-size: 17px; line-height: 1.55; -webkit-font-smoothing: antialiased;
}
a { color: var(--brand); }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 3px solid var(--focus); outline-offset: 2px; border-radius: 4px; }
img, svg { max-width: 100%; height: auto; }

.wrap { max-width: 800px; margin: 0 auto; padding: 0 16px; }
.wrap.wide { max-width: 1040px; }

/* Header */
.site-header { background: var(--brand); color: var(--brand-ink); }
.site-header .wrap { display: flex; align-items: center; justify-content: space-between; gap: 16px; min-height: 60px; }
.logo { display: inline-flex; align-items: center; gap: 10px; color: inherit; text-decoration: none; font-weight: 700; letter-spacing: .01em; font-size: 1.15rem; }
.logo .mark { width: 30px; height: 30px; border-radius: 7px; background: var(--accent); color: var(--accent-ink); display: grid; place-items: center; font-weight: 800; font-family: var(--mono); font-size: .95rem; }
.site-nav a { color: inherit; text-decoration: none; opacity: .9; margin-left: 18px; font-size: .95rem; }
.site-nav a:hover { opacity: 1; text-decoration: underline; }
@media (max-width: 520px) { .site-nav a { margin-left: 12px; font-size: .9rem; } }

/* Page head */
.page-head { padding: 28px 0 8px; }
.crumbs { font-size: .85rem; color: var(--muted); margin: 0 0 10px; }
.crumbs a { color: var(--muted); }
h1 { font-size: clamp(1.6rem, 2.6vw + 1rem, 2.3rem); line-height: 1.15; margin: 0 0 10px; letter-spacing: -.01em; }
.lede { font-size: 1.1rem; color: var(--muted); margin: 0 0 18px; }

/* Calculator */
.calc { display: grid; gap: 18px; margin: 12px 0 28px; }
@media (min-width: 720px) { .calc { grid-template-columns: 1fr 1fr; align-items: start; } }
.calc-form, .results { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 18px; box-shadow: var(--shadow); }
.calc-form { display: grid; gap: 14px; }
.field label { display: block; font-weight: 600; font-size: .95rem; margin-bottom: 6px; }
.control { display: flex; align-items: stretch; }
.control input, .control select {
  flex: 1; min-width: 0; font: inherit; font-size: 1.1rem; padding: 10px 12px; border: 1px solid var(--line);
  border-radius: 8px; background: var(--bg); color: var(--text);
}
.control .unit { display: flex; align-items: center; padding: 0 12px; background: var(--surface-2); border: 1px solid var(--line); border-left: 0; border-radius: 0 8px 8px 0; color: var(--muted); font-size: .95rem; white-space: nowrap; }
.control input:has(+ .unit), .control select:has(+ .unit) { border-radius: 8px 0 0 8px; }
.help { margin: 6px 0 0; font-size: .85rem; color: var(--muted); }

.results h2 { margin: 0 0 12px; font-size: 1.1rem; text-transform: uppercase; letter-spacing: .06em; color: var(--muted); }
.results dl { margin: 0; display: grid; gap: 10px; }
.result { display: grid; grid-template-columns: 1fr auto; gap: 4px 12px; align-items: baseline; padding: 10px 0; border-top: 1px solid var(--line); }
.result:first-child { border-top: 0; padding-top: 0; }
.result dt { margin: 0; color: var(--muted); font-size: .95rem; }
.result dd { margin: 0; font-family: var(--mono); font-size: 1.15rem; font-weight: 600; text-align: right; font-variant-numeric: tabular-nums; }
.result dd .unit { font-family: var(--sans); font-weight: 500; color: var(--muted); font-size: .9rem; }
.result.primary { background: var(--surface-2); border: 0; border-radius: 8px; padding: 14px; }
.result.primary dt { font-weight: 600; color: var(--text); }
.result.primary dd { font-size: 1.7rem; color: var(--brand); }
.result .note { grid-column: 1 / -1; margin: 0; font-size: .85rem; color: var(--muted); }
.result.na dd { color: var(--muted); }
.assumptions { margin-top: 14px; font-size: .9rem; }
.assumptions summary { cursor: pointer; font-weight: 600; color: var(--brand); }
.assumptions ul { margin: 8px 0 0; padding-left: 20px; color: var(--muted); }
.actions { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 16px; }
button { font: inherit; font-size: .95rem; padding: 9px 14px; border-radius: 8px; border: 1px solid var(--line); background: var(--surface-2); color: var(--text); cursor: pointer; }
button.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); font-weight: 600; }
button.quiet { background: transparent; }
button:hover { filter: brightness(.97); }
.toast { margin-top: 10px; font-size: .9rem; color: var(--ok); min-height: 1.2em; opacity: 0; transition: opacity .2s; }
.toast.show { opacity: 1; }

/* Article */
.article { max-width: 720px; }
.article h2 { font-size: 1.35rem; margin: 32px 0 10px; }
.article h3 { font-size: 1.1rem; margin: 22px 0 8px; }
.article table { width: 100%; border-collapse: collapse; margin: 12px 0 18px; font-size: .95rem; }
.article th, .article td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--line); vertical-align: top; }
.article th { background: var(--surface-2); font-weight: 600; }
.article td.num, .article th.num { text-align: right; font-variant-numeric: tabular-nums; }
.formula { font-family: var(--mono); font-size: .95rem; background: var(--surface-2); border: 1px solid var(--line); border-radius: 8px; padding: 10px 14px; overflow-x: auto; }
.callout { border-left: 4px solid var(--accent); background: var(--surface); padding: 12px 16px; border-radius: 0 8px 8px 0; margin: 16px 0; }
.callout.builder { border-left-color: var(--brand); }
.callout strong { display: block; margin-bottom: 4px; }
.faq details { border-top: 1px solid var(--line); padding: 10px 0; }
.faq details:last-child { border-bottom: 1px solid var(--line); }
.faq summary { cursor: pointer; font-weight: 600; }
.faq details p { margin: 8px 0 0; }
.related { margin: 30px 0; }
.related h2 { font-size: 1.1rem; margin-bottom: 10px; }
.card-grid { display: grid; gap: 12px; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); padding: 0; margin: 0; list-style: none; }
.card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 14px 16px; }
.card a { text-decoration: none; font-weight: 600; }
.card p { margin: 6px 0 0; font-size: .9rem; color: var(--muted); }
.disclaimer-line { font-size: .85rem; color: var(--muted); margin: 26px 0; }

/* Ad slots stay collapsed until ads are enabled */
.ad-slot { min-height: 0; margin: 0; }
.ad-slot.active { min-height: 90px; margin: 18px 0; }

/* Home */
.hero { padding: 40px 0 16px; }
.hero h1 { font-size: clamp(1.9rem, 3vw + 1rem, 2.8rem); }
.hero .lede { max-width: 620px; }
.group { margin: 26px 0; }
.group h2 { font-size: 1.15rem; text-transform: uppercase; letter-spacing: .06em; color: var(--muted); margin: 0 0 10px; }

/* Footer */
.site-footer { border-top: 1px solid var(--line); margin-top: 40px; padding: 24px 0 40px; color: var(--muted); font-size: .9rem; }
.site-footer .wrap { display: flex; flex-wrap: wrap; gap: 8px 22px; justify-content: space-between; }
.site-footer a { color: var(--muted); }

/* Print */
@media print {
  .site-header, .site-footer, .actions, .related, .ad-slot, .crumbs { display: none !important; }
  body { background: #fff; color: #000; font-size: 12pt; }
  .calc { grid-template-columns: 1fr 1fr; }
  .calc-form, .results { box-shadow: none; }
}