:root {
  --bg: #f7f8f6;
  --surface: #ffffff;
  --surface-2: #eef2ef;
  --text: #17201c;
  --muted: #56635c;
  --border: #d9e0db;
  --brand: #146c5a;
  --brand-ink: #ffffff;
  --brand-soft: #e2f1ec;
  --accent: #c2410c;
  --focus: #2563eb;
  --radius: 12px;
  --shadow: 0 1px 2px rgba(16, 24, 20, .06), 0 4px 16px rgba(16, 24, 20, .05);
  --maxw: 1080px;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #101513;
    --surface: #161d1a;
    --surface-2: #1d2622;
    --text: #e7ede9;
    --muted: #9fb0a7;
    --border: #2b3732;
    --brand: #4cc3a5;
    --brand-ink: #0b1210;
    --brand-soft: #18302a;
    --accent: #fb923c;
    --shadow: none;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #101513; --surface: #161d1a; --surface-2: #1d2622; --text: #e7ede9; --muted: #9fb0a7;
  --border: #2b3732; --brand: #4cc3a5; --brand-ink: #0b1210; --brand-soft: #18302a; --accent: #fb923c;
  --shadow: none; color-scheme: dark;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 17px/1.65 system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}
a { color: var(--brand); text-underline-offset: 2px; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 3px solid var(--focus); outline-offset: 2px; border-radius: 4px; }
img, svg { max-width: 100%; }
h1, h2, h3 { line-height: 1.25; letter-spacing: -.01em; }
h1 { font-size: clamp(1.8rem, 4vw, 2.5rem); margin: .2em 0 .4em; }
h2 { font-size: 1.45rem; margin: 2em 0 .5em; }
h3 { font-size: 1.12rem; margin: 1.5em 0 .3em; }
p, ul, ol { margin: 0 0 1em; }
small, .muted { color: var(--muted); }

.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 16px; }
.skip { position: absolute; left: -9999px; }
.skip:focus { left: 16px; top: 8px; background: var(--surface); padding: 8px 12px; z-index: 10; }

/* Header */
.site-header { background: var(--surface); border-bottom: 1px solid var(--border); }
.site-header .wrap { display: flex; align-items: center; justify-content: space-between; gap: 16px; min-height: 64px; flex-wrap: wrap; }
.logo { display: flex; align-items: center; gap: 10px; font-weight: 750; font-size: 1.15rem; color: var(--text); text-decoration: none; }
.logo svg { width: 30px; height: 30px; flex: none; }
.logo b { color: var(--brand); }
.nav { display: flex; gap: 18px; flex-wrap: wrap; font-size: .95rem; }
.nav a { color: var(--muted); text-decoration: none; padding: 6px 0; }
.nav a:hover, .nav a[aria-current] { color: var(--text); }

/* Breadcrumb */
.crumbs { font-size: .88rem; color: var(--muted); margin: 18px 0 0; }
.crumbs a { color: var(--muted); }

/* Hero */
.hero { padding: 48px 0 24px; }
.hero p.lead { font-size: 1.15rem; color: var(--muted); max-width: 680px; }
.badges { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 18px; }
.badge { background: var(--brand-soft); color: var(--text); border-radius: 999px; padding: 4px 12px; font-size: .85rem; }

/* Cards grid */
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); gap: 16px; margin: 24px 0 48px; }
.card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 20px; box-shadow: var(--shadow); text-decoration: none; color: var(--text); display: flex; flex-direction: column; gap: 6px; transition: border-color .15s, transform .15s; }
.card:hover { border-color: var(--brand); transform: translateY(-2px); }
.card .icon { font-size: 1.6rem; }
.card h3 { margin: 4px 0 0; }
.card p { margin: 0; color: var(--muted); font-size: .95rem; }

/* Layout for tool pages */
.tool-layout { display: grid; grid-template-columns: minmax(0, 1fr); gap: 24px; margin: 8px 0 32px; }
@media (min-width: 900px) { .tool-layout { grid-template-columns: minmax(0, 1.05fr) minmax(0, .95fr); align-items: start; } .results { position: sticky; top: 16px; } }

.panel { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 20px; box-shadow: var(--shadow); }
.panel h2 { margin-top: 0; font-size: 1.15rem; }

.field { margin-bottom: 16px; }
.field label, .field .label { display: block; font-weight: 600; font-size: .95rem; margin-bottom: 6px; }
.field .hint { font-size: .85rem; color: var(--muted); margin-top: 4px; }
.row { display: grid; grid-template-columns: repeat(auto-fit, minmax(130px, 1fr)); gap: 12px; }
input[type="number"], select {
  width: 100%; font: inherit; color: var(--text); background: var(--bg);
  border: 1px solid var(--border); border-radius: 8px; padding: 10px 12px; min-height: 44px;
}
input[type="number"]:focus, select:focus { border-color: var(--brand); }
.seg { display: flex; flex-wrap: wrap; gap: 8px; }
.seg label { display: inline-flex; align-items: center; gap: 6px; border: 1px solid var(--border); border-radius: 8px; padding: 8px 12px; cursor: pointer; font-weight: 500; background: var(--bg); min-height: 44px; }
.seg input { accent-color: var(--brand); }
.seg label:has(input:checked) { border-color: var(--brand); background: var(--brand-soft); }

/* Results */
.results .big { font-size: clamp(1.9rem, 5vw, 2.6rem); font-weight: 800; letter-spacing: -.02em; color: var(--brand); line-height: 1.1; margin: 4px 0; font-variant-numeric: tabular-nums; }
.results .sub { color: var(--muted); font-size: .95rem; }
.kv { width: 100%; border-collapse: collapse; margin: 16px 0 8px; font-variant-numeric: tabular-nums; }
.kv td { padding: 8px 0; border-bottom: 1px solid var(--border); vertical-align: top; }
.kv td:last-child { text-align: right; font-weight: 600; white-space: nowrap; padding-left: 12px; }
.note { font-size: .85rem; color: var(--muted); }
.cta { margin-top: 16px; background: var(--brand-soft); border-radius: 10px; padding: 14px 16px; font-size: .95rem; }
.cta strong { display: block; margin-bottom: 4px; }

/* Article */
.article { max-width: 760px; }
.article table { width: 100%; border-collapse: collapse; margin: 12px 0 20px; font-size: .95rem; display: block; overflow-x: auto; }
.article th, .article td { text-align: left; padding: 10px 12px; border-bottom: 1px solid var(--border); }
.article th { background: var(--surface-2); font-weight: 650; }
.article .formula { background: var(--surface-2); border-radius: 8px; padding: 12px 14px; font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: .9rem; overflow-x: auto; }
details { border-top: 1px solid var(--border); padding: 12px 0; }
details summary { cursor: pointer; font-weight: 600; }
details p { margin: 8px 0 0; }
.sources { font-size: .9rem; color: var(--muted); }
.updated { font-size: .88rem; color: var(--muted); }

/* Ad slot placeholder (kept empty until AdSense is approved; reserves no space) */
.ad-slot:empty { display: none; }
.ad-slot { margin: 24px 0; min-height: 250px; }

/* Footer */
.site-footer { border-top: 1px solid var(--border); background: var(--surface); margin-top: 48px; padding: 32px 0; font-size: .92rem; color: var(--muted); }
.site-footer .cols { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: 20px; }
.site-footer h4 { color: var(--text); margin: 0 0 8px; font-size: .95rem; }
.site-footer ul { list-style: none; padding: 0; margin: 0; }
.site-footer li { margin: 4px 0; }
.site-footer a { color: var(--muted); }

@media print { .site-header, .site-footer, .ad-slot, .cta { display: none; } }