/* TireMath — mobile-first design system. No frameworks. */
:root {
  --ink: #1c2430;
  --muted: #5b6675;
  --line: #dfe5ec;
  --bg: #f6f8fa;
  --card: #ffffff;
  --accent: #c2410c;      /* burnt orange */
  --accent-dark: #9a3412;
  --ok: #166534;
  --ok-bg: #dcfce7;
  --warn: #92400e;
  --warn-bg: #fef3c7;
  --bad: #991b1b;
  --bad-bg: #fee2e2;
  --radius: 10px;
  --wrap: 860px;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.6;
}
.wrap { max-width: var(--wrap); margin: 0 auto; padding: 0 1rem; }

/* Header */
.site-header { background: var(--ink); color: #fff; }
.site-header .wrap { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: .5rem; padding-top: .8rem; padding-bottom: .8rem; }
.brand { color: #fff; text-decoration: none; font-weight: 800; font-size: 1.35rem; letter-spacing: .2px; }
.brand span { color: #fb923c; }
.site-nav { display: flex; gap: 1rem; flex-wrap: wrap; }
.site-nav a { color: #cbd5e1; text-decoration: none; font-size: .95rem; }
.site-nav a:hover { color: #fff; text-decoration: underline; }

/* Hero */
.hero { background: linear-gradient(180deg, #232f40, #1c2430); color: #fff; padding: 2rem 0 2.25rem; }
.hero h1 { margin: 0 0 .5rem; font-size: 1.7rem; line-height: 1.25; }
.hero p { margin: 0; color: #cbd5e1; max-width: 60ch; }
.hero .fine { margin-top: .75rem; font-size: .85rem; color: #94a3b8; }

/* Cards & layout */
main.wrap { padding-top: 1.25rem; padding-bottom: 2rem; }
.card { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 1.25rem; margin: 1.25rem 0; box-shadow: 0 1px 2px rgba(16,24,40,.05); }
.card h2 { margin-top: 0; font-size: 1.25rem; }
.card h3 { font-size: 1.05rem; margin-bottom: .4rem; }

/* Forms */
.field { margin-bottom: .9rem; }
.field label { display: block; font-weight: 600; margin-bottom: .3rem; font-size: .95rem; }
.field .hint { font-weight: 400; color: var(--muted); font-size: .85rem; }
input[type="text"], select {
  width: 100%; padding: .65rem .7rem; font-size: 1rem;
  border: 1px solid var(--line); border-radius: 8px; background: #fff; color: var(--ink);
}
input[type="text"]:focus, select:focus { outline: 2px solid var(--accent); outline-offset: 1px; border-color: var(--accent); }
.grid2 { display: grid; grid-template-columns: 1fr; gap: 0 1rem; }
@media (min-width: 640px) { .grid2 { grid-template-columns: 1fr 1fr; } }
.btn {
  display: inline-block; background: var(--accent); color: #fff; border: none;
  padding: .7rem 1.4rem; font-size: 1rem; font-weight: 700; border-radius: 8px; cursor: pointer;
}
.btn:hover { background: var(--accent-dark); }
.error { color: var(--bad); font-size: .9rem; margin-top: .35rem; min-height: 1.2em; }

/* Results */
.results { display: none; }
.results.show { display: block; }
.verdict { border-radius: var(--radius); padding: .9rem 1rem; font-weight: 600; margin: 1rem 0; }
.verdict.ok { background: var(--ok-bg); color: var(--ok); border: 1px solid #86efac; }
.verdict.warn { background: var(--warn-bg); color: var(--warn); border: 1px solid #fcd34d; }
.verdict.bad { background: var(--bad-bg); color: var(--bad); border: 1px solid #fca5a5; }
table.specs { width: 100%; border-collapse: collapse; font-size: .92rem; margin: .75rem 0; }
table.specs th, table.specs td { border: 1px solid var(--line); padding: .5rem .6rem; text-align: right; }
table.specs th:first-child, table.specs td:first-child { text-align: left; }
table.specs thead th { background: #eef2f6; }
.delta-up { color: var(--bad); font-weight: 600; }
.delta-down { color: var(--ok); font-weight: 600; }
.delta-flat { color: var(--muted); }

/* Speedo table */
.speedo-note { font-size: .88rem; color: var(--muted); }

/* Plus/minus sizing */
.sizing-grid { display: grid; grid-template-columns: 1fr; gap: .75rem; margin-top: .75rem; }
@media (min-width: 640px) { .sizing-grid { grid-template-columns: 1fr 1fr; } }
.size-opt { border: 1px solid var(--line); border-radius: 8px; padding: .7rem .8rem; background: #fbfcfe; }
.size-opt strong { font-size: 1.05rem; }
.size-opt .tag { display: inline-block; font-size: .75rem; font-weight: 700; background: #e0e7ff; color: #3730a3; border-radius: 999px; padding: .1rem .55rem; margin-left: .4rem; vertical-align: middle; }

/* FAQ */
.faq details { border: 1px solid var(--line); border-radius: 8px; margin-bottom: .6rem; background: #fff; }
.faq summary { cursor: pointer; padding: .8rem 1rem; font-weight: 600; }
.faq summary::-webkit-details-marker { color: var(--accent); }
.faq .answer { padding: 0 1rem 1rem; color: #334155; }

/* Ad slots (placeholders) */
.ad-slot {
  border: 1px dashed #b6c2cf; background: #eef2f6; color: var(--muted);
  text-align: center; padding: 1.4rem 1rem; margin: 1.25rem 0; border-radius: 8px; font-size: .85rem;
}

/* Affiliate placeholder */
.affil { border: 1px solid var(--line); border-radius: var(--radius); background: #fffbeb; padding: 1rem 1.25rem; margin: 1.25rem 0; }
.affil h2, .affil h3 { margin-top: 0; }
.affil ul { margin: .5rem 0; padding-left: 1.2rem; }
.affil a { color: var(--accent-dark); }

/* Article pages */
.article h2 { font-size: 1.3rem; margin-top: 1.6rem; }
.article h3 { font-size: 1.08rem; margin-top: 1.2rem; }
.article table { width: 100%; border-collapse: collapse; font-size: .92rem; margin: .75rem 0; }
.article table th, .article table td { border: 1px solid var(--line); padding: .5rem .6rem; text-align: left; }
.article table thead th { background: #eef2f6; }
.callout { border-left: 4px solid var(--accent); background: #fff7ed; padding: .8rem 1rem; border-radius: 0 8px 8px 0; margin: 1rem 0; }
.callout.caution { border-left-color: var(--bad); background: var(--bad-bg); }
.breadcrumb { font-size: .85rem; color: var(--muted); margin: 1rem 0 0; }
.breadcrumb a { color: var(--accent-dark); }

/* Footer */
.site-footer { background: var(--ink); color: #94a3b8; font-size: .85rem; padding: 1.75rem 0; margin-top: 1rem; }
.site-footer a { color: #cbd5e1; }
.site-footer .disclaimer { max-width: 70ch; }
.toc { columns: 1; }
@media (min-width: 640px) { .toc { columns: 2; } }
.toc li { margin-bottom: .35rem; }