/* Static (crawlable) pages. Same visual language as the study board; no JavaScript required. */
:root {
  --bg: #f5f6f8; --surface: #fff; --surface-2: #f0f2f5; --text: #141922; --muted: #5a6575; --border: #e2e6ec; --border-strong: #cdd3dc;
  --accent: #0b7a85; --accent-ink: #fff; --accent-strong: #095f68; --accent-soft: #dff1f3; --good: #17784a; --good-soft: #e2f4ea; --warn-soft: #fdf2d8;
  --font: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif; --read: ui-serif, "Iowan Old Style", Georgia, serif;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root { --bg: #0c1117; --surface: #141b24; --surface-2: #1b2430; --text: #e7ebf1; --muted: #9aa5b4; --border: #243040; --border-strong: #344256;
    --accent: #3dbfcb; --accent-ink: #04242a; --accent-strong: #7ad8e1; --accent-soft: #11323a; --good: #4cc38a; --good-soft: #10301f; --warn-soft: #33270d; color-scheme: dark; }
}
* { box-sizing: border-box; }
body { margin: 0; background: var(--bg); color: var(--text); font: 16px/1.65 var(--font); -webkit-font-smoothing: antialiased; }
a { color: var(--accent-strong); text-underline-offset: 2px; } a:hover { color: var(--accent); }
.wrap { max-width: 960px; margin: 0 auto; padding: 0 20px; }
.skip { position: absolute; left: -999px; top: 8px; background: var(--surface); padding: 8px 12px; border-radius: 8px; z-index: 10; } .skip:focus { left: 8px; }
:focus-visible { outline: 3px solid color-mix(in srgb, var(--accent) 50%, transparent); outline-offset: 2px; border-radius: 6px; }

.site-header { background: var(--surface); border-bottom: 1px solid var(--border); position: sticky; top: 0; z-index: 5; }
.bar { display: flex; align-items: center; gap: 16px; min-height: 60px; flex-wrap: wrap; padding-top: 6px; padding-bottom: 6px; }
.logo { display: flex; align-items: center; gap: 10px; font-weight: 750; letter-spacing: -.02em; text-decoration: none; color: var(--text); font-size: 1.1rem; }
.mark { width: 30px; height: 30px; border-radius: 9px; background: linear-gradient(135deg, var(--accent), var(--accent-strong)); color: var(--accent-ink); display: grid; place-items: center; font-size: .8rem; font-weight: 800; }
.nav { display: flex; gap: 4px; margin-left: auto; flex-wrap: wrap; } .nav a { padding: 8px 12px; border-radius: 9px; color: var(--muted); text-decoration: none; font-weight: 560; font-size: .95rem; }
.nav a:hover { background: var(--surface-2); color: var(--text); } .nav a[aria-current="page"] { background: var(--accent-soft); color: var(--accent-strong); }
@media (max-width: 760px) { .nav { order: 3; width: 100%; margin: 0; overflow-x: auto; flex-wrap: nowrap; } .bar .btn { margin-left: auto; } }

main { padding-top: 24px; padding-bottom: 56px; min-height: 60vh; }
h1 { font-size: clamp(1.6rem, 4vw, 2.3rem); line-height: 1.2; letter-spacing: -.02em; margin: .4em 0 .5em; }
h2 { font-size: 1.35rem; line-height: 1.3; margin: 1.8em 0 .5em; letter-spacing: -.01em; } h3 { font-size: 1.1rem; margin: 1.2em 0 .4em; }
.lead { font-size: 1.15rem; color: var(--muted); max-width: 70ch; } .muted { color: var(--muted); } .small { font-size: .86rem; color: var(--muted); }
.crumbs { font-size: .86rem; color: var(--muted); margin-bottom: 10px; } .crumbs a { color: var(--muted); }
.eyebrow { font-size: .8rem; text-transform: uppercase; letter-spacing: .06em; font-weight: 700; color: var(--accent-strong); margin: 0; } .eyebrow a { color: inherit; }
.prose { max-width: 74ch; } .prose h2 { margin-top: 1.6em; } .prose li { margin: .3em 0; }
.source { font-size: .88rem; color: var(--muted); border-top: 1px solid var(--border); padding-top: 14px; margin-top: 28px; }

.btn { display: inline-flex; align-items: center; justify-content: center; padding: 10px 18px; border-radius: 10px; border: 1px solid var(--border-strong); background: var(--surface); color: var(--text); text-decoration: none; font-weight: 600; min-height: 42px; }
.btn:hover { background: var(--surface-2); color: var(--text); } .btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); } .btn.primary:hover { background: var(--accent-strong); border-color: var(--accent-strong); color: var(--accent-ink); } .btn.sm { padding: 6px 14px; min-height: 36px; font-size: .92rem; }
.cta-row { display: flex; gap: 10px; flex-wrap: wrap; margin: 18px 0; }

.hero { padding: 24px 0 8px; } .hero h1 { font-size: clamp(1.9rem, 5vw, 2.9rem); max-width: 20ch; }
.hero-stats { display: flex; flex-wrap: wrap; gap: 10px 28px; list-style: none; padding: 0; margin: 20px 0 0; color: var(--muted); } .hero-stats b { color: var(--text); font-size: 1.4rem; margin-right: 4px; }
.cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 14px; margin: 16px 0; } .cards.three { grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); }
.card { display: block; background: var(--surface); border: 1px solid var(--border); border-radius: 14px; padding: 16px 18px; text-decoration: none; color: var(--text); }
a.card:hover { border-color: var(--accent); background: var(--accent-soft); color: var(--text); } .card h2, .card h3 { margin: 0 0 6px; font-size: 1.05rem; } .card p { margin: 0 0 6px; color: var(--muted); font-size: .94rem; }

.table-wrap { overflow-x: auto; } table { width: 100%; border-collapse: collapse; font-size: .95rem; margin: 12px 0; background: var(--surface); border: 1px solid var(--border); border-radius: 10px; }
th, td { text-align: left; padding: 9px 12px; border-bottom: 1px solid var(--border); vertical-align: top; } th { background: var(--surface-2); font-size: .8rem; text-transform: uppercase; letter-spacing: .04em; color: var(--muted); } td.r, th.r { text-align: right; }

.link-list { list-style: none; padding: 0; margin: 8px 0; } .link-list li { padding: 7px 0; border-bottom: 1px solid var(--border); } .link-list.compact li { padding: 4px 0; font-size: .95rem; }
ul.cols { columns: 2; list-style: none; padding: 0; } @media (max-width: 600px) { ul.cols { columns: 1; } }
.pager { display: flex; justify-content: space-between; gap: 12px; margin-top: 36px; padding-top: 16px; border-top: 1px solid var(--border); }
.alpha a { display: inline-block; padding: 2px 8px; font-weight: 700; } dt { font-weight: 700; margin-top: 12px; } dd { margin: 2px 0 0 0; color: var(--muted); }
.faq h2, .faq h3 { margin: 1em 0 .2em; font-size: 1.1rem; } .faq p { margin: 0; }

/* question pages */
.q-page h1 { font-family: var(--read); font-size: clamp(1.3rem, 3.2vw, 1.75rem); line-height: 1.45; font-weight: 600; }
.q-page .context, .q-page .stem { font-family: var(--read); } .context { color: var(--muted); font-style: italic; }
.case-box { background: var(--surface); border: 1px solid var(--border); border-left: 4px solid var(--accent); border-radius: 12px; padding: 4px 18px 10px; margin: 16px 0; } .case-box h2 { font-size: 1.05rem; margin: 12px 0 6px; } .case-box p { margin: 6px 0; }
.case-q { margin-top: 26px; } .case-q h2, .case-q h3 { margin-top: 0; font-family: var(--read); font-weight: 600; }
.options { padding-left: 1.6em; margin: 14px 0; } .options li { padding: 9px 12px 9px 6px; margin: 8px 0; background: var(--surface); border: 1px solid var(--border); border-radius: 10px; } .options li::marker { font-weight: 700; color: var(--accent-strong); }
.qimg { max-width: 100%; max-height: 380px; border-radius: 10px; border: 1px solid var(--border); background: #fff; margin: 12px 0; }
details.answer { margin: 14px 0; background: var(--surface); border: 1px solid var(--border); border-radius: 12px; padding: 12px 16px; } details.answer summary { cursor: pointer; font-weight: 650; color: var(--accent-strong); }
.correct { background: var(--good-soft); padding: 10px 14px; border-radius: 10px; margin: 12px 0 8px; } .explain { margin: 10px 0; } .per-option { padding-left: 1.2em; color: var(--muted); } .note { background: var(--warn-soft); padding: 8px 12px; border-radius: 8px; font-size: .94rem; }

.site-footer { border-top: 1px solid var(--border); background: var(--surface); padding: 24px 0 40px; color: var(--muted); font-size: .85rem; line-height: 1.6; } .site-footer p { margin: 0 0 10px; } .site-footer a { color: var(--muted); }