:root {
  --bg: #f6f6f2;
  --card: #ffffff;
  --ink: #1b1d1f;
  --muted: #555b61;
  --line: #d8dad4;
  --accent: #0b6a4c;
  --accent-ink: #ffffff;
  --soft: #e9f2ee;
  --warn-bg: #fff4dc;
  --warn-ink: #6b4a00;
  --focus: #1f5fd1;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #111315;
    --card: #1a1d20;
    --ink: #e8e9e5;
    --muted: #a7adb2;
    --line: #30353a;
    --accent: #55c79e;
    --accent-ink: #0d1a14;
    --soft: #17261f;
    --warn-bg: #33290f;
    --warn-ink: #f3d68b;
    --focus: #8ab4ff;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #111315;
  --card: #1a1d20;
  --ink: #e8e9e5;
  --muted: #a7adb2;
  --line: #30353a;
  --accent: #55c79e;
  --accent-ink: #0d1a14;
  --soft: #17261f;
  --warn-bg: #33290f;
  --warn-ink: #f3d68b;
  --focus: #8ab4ff;
  color-scheme: dark;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 17px/1.6 system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}
.wrap { max-width: 46rem; margin: 0 auto; padding: 0 16px; }
a { color: var(--accent); text-underline-offset: 2px; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 3px solid var(--focus); outline-offset: 2px; border-radius: 3px; }
.skip { position: absolute; left: -999px; top: 0; background: var(--card); padding: 8px 12px; z-index: 10; }
.skip:focus { left: 8px; top: 8px; }

.site-header { border-bottom: 1px solid var(--line); background: var(--card); }
.site-header .wrap { display: flex; flex-wrap: wrap; align-items: center; gap: 6px 18px; padding-top: 12px; padding-bottom: 12px; }
.brand { font-weight: 700; color: var(--ink); text-decoration: none; display: inline-flex; align-items: center; gap: 8px; margin-right: auto; }
.brand svg { width: 22px; height: 22px; }
.site-header nav { display: flex; flex-wrap: wrap; gap: 4px 14px; font-size: 15px; }
.site-header nav a { color: var(--muted); text-decoration: none; padding: 4px 0; }
.site-header nav a:hover { color: var(--ink); }
.site-header nav a[aria-current="page"] { color: var(--ink); font-weight: 600; box-shadow: inset 0 -2px 0 var(--accent); }

main { padding: 28px 0 40px; }
h1 { font-size: 1.85rem; line-height: 1.2; margin: 0 0 12px; letter-spacing: -0.01em; }
h2 { font-size: 1.3rem; line-height: 1.3; margin: 40px 0 10px; }
h3 { font-size: 1.05rem; margin: 24px 0 6px; }
p, ul, ol { margin: 0 0 14px; }
.lede { font-size: 1.08rem; }
.muted { color: var(--muted); }
.small { font-size: 0.9rem; }

.calc { background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 18px 16px; margin: 22px 0 8px; }
.calc fieldset { border: 0; padding: 0; margin: 0; min-width: 0; }
.calc legend { font-weight: 700; font-size: 1.05rem; padding: 0; margin-bottom: 4px; }
.note { background: var(--soft); border-radius: 8px; padding: 10px 12px; font-size: 0.93rem; margin: 6px 0 14px; }
.fields { display: grid; grid-template-columns: 1fr; gap: 14px; }
.field { min-width: 0; }
.field label { display: block; font-weight: 600; font-size: 0.95rem; margin-bottom: 4px; }
.field .hint { display: block; color: var(--muted); font-size: 0.85rem; font-weight: 400; }
.input { display: flex; align-items: stretch; border: 1px solid var(--line); border-radius: 8px; background: var(--bg); overflow: hidden; }
.input:focus-within { outline: 3px solid var(--focus); outline-offset: 1px; }
.input input { flex: 1 1 auto; width: 100%; min-width: 0; border: 0; background: transparent; color: var(--ink); font: inherit; font-variant-numeric: tabular-nums; padding: 10px 12px; }
.input input:focus { outline: none; }
.input .unit { display: flex; align-items: center; padding: 0 12px; color: var(--muted); border-left: 1px solid var(--line); font-size: 0.95rem; }
.input .unit.pre { border-left: 0; border-right: 1px solid var(--line); }
.actions { margin-top: 14px; display: flex; gap: 10px; flex-wrap: wrap; }
button { font: inherit; font-size: 0.95rem; border-radius: 8px; padding: 8px 14px; cursor: pointer; border: 1px solid var(--line); background: var(--card); color: var(--ink); }
button:hover { border-color: var(--muted); }

.results { margin: 18px 0 0; padding-top: 16px; border-top: 1px solid var(--line); }
.results h3 { margin: 0 0 10px; font-size: 1rem; }
.results dl { display: grid; grid-template-columns: 1fr; gap: 8px; margin: 0; }
.results dl > div { display: flex; justify-content: space-between; align-items: baseline; gap: 12px; padding: 8px 0; border-bottom: 1px dashed var(--line); }
.results dt { color: var(--muted); font-size: 0.95rem; }
.results dd { margin: 0; font-weight: 700; font-size: 1.15rem; font-variant-numeric: tabular-nums; text-align: right; white-space: nowrap; }
.results .key dd { color: var(--accent); font-size: 1.45rem; }
.status { margin: 12px 0 0; padding: 10px 12px; border-radius: 8px; font-size: 0.93rem; background: var(--soft); }
.status.warn, .error { background: var(--warn-bg); color: var(--warn-ink); }
.error { padding: 10px 12px; border-radius: 8px; margin: 12px 0 0; font-size: 0.93rem; }
.error:empty, .status:empty { display: none; }

.formula { background: var(--card); border: 1px solid var(--line); border-radius: 8px; padding: 12px 14px; font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: 0.88rem; line-height: 1.7; overflow-wrap: anywhere; }
.formula p { margin: 0; }

table { width: 100%; border-collapse: collapse; margin: 8px 0 16px; font-size: 0.93rem; }
th, td { text-align: left; padding: 8px 6px; border-bottom: 1px solid var(--line); vertical-align: top; }
th { font-weight: 600; }
td.num { white-space: nowrap; font-variant-numeric: tabular-nums; }

.sources { font-size: 0.93rem; padding-left: 20px; }
.sources li { margin-bottom: 8px; }

.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; }

.card-links { list-style: none; padding: 0; display: grid; gap: 10px; }
.card-links a { display: block; padding: 12px 14px; border: 1px solid var(--line); border-radius: 10px; background: var(--card); text-decoration: none; color: var(--ink); }
.card-links a span { display: block; color: var(--muted); font-size: 0.9rem; }
.card-links a:hover { border-color: var(--accent); }

.site-footer { border-top: 1px solid var(--line); padding: 22px 0 32px; color: var(--muted); font-size: 0.88rem; }
.site-footer nav { display: flex; gap: 14px; flex-wrap: wrap; margin-bottom: 8px; }
.site-footer a { color: var(--muted); }
.site-footer p { margin: 0 0 6px; }

@media (min-width: 640px) {
  h1 { font-size: 2.2rem; }
  .calc { padding: 22px 24px; }
  .fields { grid-template-columns: 1fr 1fr; gap: 16px 20px; }
  .results dl { grid-template-columns: 1fr 1fr; column-gap: 24px; }
  .card-links { grid-template-columns: 1fr 1fr; }
}
@media (prefers-reduced-motion: no-preference) {
  .card-links a { transition: border-color 0.15s; }
}