/* TrueToolCalc — shared styles. No frameworks, no build step. */
:root {
  --bg: #f7f8fa;
  --card: #ffffff;
  --ink: #1e2430;
  --muted: #5b6472;
  --accent: #1a6fd4;
  --accent-dark: #1259ab;
  --border: #e2e6ec;
  --warn-bg: #fff7e6;
  --warn-border: #f0c36d;
  --radius: 10px;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.65;
}
a { color: var(--accent); }
.wrap { max-width: 860px; margin: 0 auto; padding: 0 20px; }

/* Header / nav */
.site-header { background: var(--card); border-bottom: 1px solid var(--border); }
.site-header .wrap { display: flex; align-items: center; justify-content: space-between; padding-top: 14px; padding-bottom: 14px; }
.brand { font-weight: 700; font-size: 1.15rem; color: var(--ink); text-decoration: none; }
.brand span { color: var(--accent); }
.site-nav a { margin-left: 18px; text-decoration: none; color: var(--muted); font-size: 0.95rem; }
.site-nav a:hover { color: var(--accent); }

/* Hero */
.hero { padding: 40px 0 24px; }
.hero h1 { margin: 0 0 10px; font-size: 1.9rem; line-height: 1.3; }
.hero p { color: var(--muted); margin: 0; max-width: 640px; }

/* Tool grid (homepage) */
.tool-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 16px; padding: 8px 0 48px; }
.tool-card {
  background: var(--card); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 18px; text-decoration: none; color: var(--ink); display: block;
}
.tool-card:hover { border-color: var(--accent); box-shadow: 0 2px 10px rgba(26,111,212,.12); }
.tool-card h2 { font-size: 1.05rem; margin: 0 0 6px; }
.tool-card p { margin: 0; font-size: 0.9rem; color: var(--muted); }

/* Calculator card */
.calc-card {
  background: var(--card); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 22px; margin: 20px 0;
}
.unit-toggle { display: flex; gap: 8px; margin-bottom: 16px; }
.unit-toggle button {
  border: 1px solid var(--border); background: var(--bg); border-radius: 6px;
  padding: 6px 14px; cursor: pointer; font-size: 0.9rem;
}
.unit-toggle button.active { background: var(--accent); color: #fff; border-color: var(--accent); }
.field { margin-bottom: 14px; }
.field label { display: block; font-weight: 600; margin-bottom: 4px; font-size: 0.95rem; }
.field .hint { font-weight: 400; color: var(--muted); font-size: 0.85rem; display: block; margin-top: 2px; }
.field input, .field select {
  width: 100%; max-width: 320px; padding: 9px 12px; font-size: 1rem;
  border: 1px solid var(--border); border-radius: 6px;
}
.calc-btn {
  background: var(--accent); color: #fff; border: none; border-radius: 6px;
  padding: 11px 26px; font-size: 1rem; cursor: pointer; margin-top: 4px;
}
.calc-btn:hover { background: var(--accent-dark); }
.results {
  margin-top: 18px; padding: 16px 18px; background: #eef5ff;
  border: 1px solid #c9def8; border-radius: 8px; display: none;
}
.results.show { display: block; }
.results h3 { margin: 0 0 8px; font-size: 1rem; }
.results .big { font-size: 1.5rem; font-weight: 700; color: var(--accent-dark); }
.results table { width: 100%; border-collapse: collapse; font-size: 0.95rem; }
.results td { padding: 5px 0; border-bottom: 1px dashed #c9def8; }
.results td:last-child { text-align: right; font-variant-numeric: tabular-nums; }

/* Content sections */
.prose section { margin: 30px 0; }
.prose h2 { font-size: 1.3rem; border-bottom: 2px solid var(--border); padding-bottom: 6px; }
.prose h3 { font-size: 1.05rem; }
.formula {
  background: var(--card); border: 1px solid var(--border); border-left: 4px solid var(--accent);
  border-radius: 6px; padding: 12px 16px; font-family: ui-monospace, Menlo, Consolas, monospace;
  overflow-x: auto; margin: 12px 0;
}
.example {
  background: var(--card); border: 1px solid var(--border); border-radius: 8px;
  padding: 16px 18px; margin: 12px 0;
}
.example ol { margin: 8px 0; padding-left: 22px; }
.example .answer { font-weight: 700; }
.notice {
  background: var(--warn-bg); border: 1px solid var(--warn-border); border-radius: 8px;
  padding: 14px 18px; margin: 16px 0; font-size: 0.95rem;
}
.faq details { background: var(--card); border: 1px solid var(--border); border-radius: 8px; margin-bottom: 10px; padding: 12px 16px; }
.faq summary { font-weight: 600; cursor: pointer; }
.related ul { columns: 2; padding-left: 20px; }
.related li { margin-bottom: 6px; break-inside: avoid; }

/* Data tables in content sections */
.data-table { width: 100%; border-collapse: collapse; font-size: 0.95rem; margin: 12px 0; background: var(--card); }
.data-table th, .data-table td { border: 1px solid var(--border); padding: 8px 12px; text-align: left; }
.data-table th { background: #eef5ff; font-weight: 700; }
.data-table td { font-variant-numeric: tabular-nums; }
.data-table caption { caption-side: bottom; font-size: 0.85rem; color: var(--muted); padding-top: 6px; text-align: left; }

/* Footer */
.site-footer { border-top: 1px solid var(--border); margin-top: 40px; padding: 22px 0 34px; color: var(--muted); font-size: 0.88rem; }
.site-footer a { color: var(--muted); }
.site-footer a:hover { color: var(--accent); }
.site-footer .wrap { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 10px; }
.breadcrumb { font-size: 0.85rem; color: var(--muted); margin: 16px 0 0; }
.breadcrumb a { color: var(--muted); }

@media (max-width: 600px) {
  .hero h1 { font-size: 1.5rem; }
  .related ul { columns: 1; }
}