:root {
  --bg: #f7f7f5;
  --surface: #ffffff;
  --surface-2: #f0f1ee;
  --text: #1c1f23;
  --muted: #5f6670;
  --border: #e2e4e0;
  --accent: #2456d6;
  --accent-soft: #e6edfc;
  --good: #1f7a4d;
  --good-soft: #e3f4ea;
  --bad: #b3261e;
  --bad-soft: #fbe7e5;
  --warn: #8a5a00;
  --warn-soft: #fdf3dc;
  --radius: 12px;
  --shadow: 0 1px 2px rgba(0,0,0,.04), 0 4px 16px rgba(0,0,0,.04);
  --font: "Inter", system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  --mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #111316; --surface: #181b1f; --surface-2: #20242a; --text: #e8eaed; --muted: #9aa2ad;
    --border: #2b3037; --accent: #7aa2ff; --accent-soft: #1d2a47; --good: #5fd39a; --good-soft: #143326;
    --bad: #ff8a80; --bad-soft: #3a1a18; --warn: #f2c063; --warn-soft: #3a2e12; --shadow: none;
  }
}
:root[data-theme="dark"] {
  --bg: #111316; --surface: #181b1f; --surface-2: #20242a; --text: #e8eaed; --muted: #9aa2ad;
  --border: #2b3037; --accent: #7aa2ff; --accent-soft: #1d2a47; --good: #5fd39a; --good-soft: #143326;
  --bad: #ff8a80; --bad-soft: #3a1a18; --warn: #f2c063; --warn-soft: #3a2e12; --shadow: none;
}

* { box-sizing: border-box; }
html { scroll-padding-top: 80px; }
body { margin: 0; background: var(--bg); color: var(--text); font: 16px/1.6 var(--font); -webkit-font-smoothing: antialiased; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
code { font-family: var(--mono); font-size: .88em; background: var(--surface-2); padding: .1em .35em; border-radius: 5px; }
h1, h2, h3, h4 { line-height: 1.25; margin: 0 0 .5em; }
h1 { font-size: clamp(1.6rem, 3.5vw, 2.3rem); letter-spacing: -.02em; }
h2 { font-size: 1.4rem; letter-spacing: -.01em; }
h3 { font-size: 1.1rem; }
.muted { color: var(--muted); font-weight: 400; }
main { max-width: 1180px; margin: 0 auto; padding: 24px 16px 64px; outline: none; }

/* Top bar */
.topbar { position: sticky; top: 0; z-index: 10; display: flex; align-items: center; gap: 16px; padding: 10px 16px; background: color-mix(in srgb, var(--bg) 88%, transparent); backdrop-filter: blur(8px); border-bottom: 1px solid var(--border); flex-wrap: wrap; }
.brand { display: flex; align-items: center; gap: 10px; color: var(--text); font-weight: 600; }
.brand:hover { text-decoration: none; }
.brand-mark { background: var(--accent); color: #fff; font-size: .75rem; font-weight: 700; padding: 4px 7px; border-radius: 7px; letter-spacing: .04em; }
:root[data-theme="dark"] .brand-mark { color: #111; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .brand-mark { color: #111; } }
.tabs { display: flex; gap: 4px; margin-left: auto; flex-wrap: wrap; }
.tabs a { padding: 6px 12px; border-radius: 8px; color: var(--muted); font-weight: 500; font-size: .95rem; }
.tabs a:hover { background: var(--surface-2); text-decoration: none; color: var(--text); }
.tabs a.active { background: var(--accent-soft); color: var(--accent); }
.theme-toggle { border: 1px solid var(--border); background: var(--surface); color: var(--text); border-radius: 8px; width: 36px; height: 34px; cursor: pointer; font-size: 1rem; }
@media (max-width: 640px) { .brand-text .muted { display: none; } .theme-toggle { margin-left: auto; } .tabs { margin-left: 0; width: 100%; order: 3; } .tabs a { padding: 6px 9px; font-size: .9rem; } }

/* Cards & layout */
.card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 20px; box-shadow: var(--shadow); }
.grid { display: grid; gap: 16px; }
.grid-2 { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
.grid-3 { grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); }
.hero { padding: 28px 0 8px; }
.hero p { max-width: 720px; color: var(--muted); font-size: 1.05rem; }
.stats { display: flex; gap: 12px; flex-wrap: wrap; margin: 20px 0; }
.stat { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 12px 16px; min-width: 120px; }
.stat b { display: block; font-size: 1.5rem; letter-spacing: -.02em; }
.stat span { color: var(--muted); font-size: .85rem; }
.section-title { display: flex; align-items: baseline; justify-content: space-between; gap: 12px; margin: 32px 0 12px; flex-wrap: wrap; }

/* Domain weight bars */
.weights { display: grid; gap: 8px; }
.weight-row { display: grid; grid-template-columns: minmax(150px, 220px) 1fr 48px; gap: 12px; align-items: center; color: var(--text); padding: 6px 8px; border-radius: 8px; }
.weight-row:hover { background: var(--surface-2); text-decoration: none; }
.bar { height: 10px; background: var(--surface-2); border-radius: 99px; overflow: hidden; }
.bar > i { display: block; height: 100%; background: var(--accent); border-radius: 99px; }
.weight-row .pct { text-align: right; font-variant-numeric: tabular-nums; color: var(--muted); font-weight: 600; }
@media (max-width: 520px) { .weight-row { grid-template-columns: 1fr 44px; } .weight-row .bar { grid-column: 1 / -1; grid-row: 2; } }

/* Study layout */
.study { display: grid; grid-template-columns: 250px 1fr; gap: 32px; align-items: start; }
.toc { position: sticky; top: 76px; max-height: calc(100vh - 96px); overflow: auto; font-size: .92rem; }
.toc a { display: block; padding: 5px 10px; border-radius: 7px; color: var(--muted); }
.toc a:hover { background: var(--surface-2); text-decoration: none; color: var(--text); }
.toc a.active { color: var(--accent); background: var(--accent-soft); font-weight: 600; }
.toc .pct { float: right; font-variant-numeric: tabular-nums; opacity: .8; }
@media (max-width: 900px) { .study { grid-template-columns: 1fr; } .toc { position: static; max-height: none; display: flex; flex-wrap: wrap; gap: 4px; } .toc a { background: var(--surface); border: 1px solid var(--border); } .toc .pct { float: none; margin-left: 6px; } }
.domain-head { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; margin-bottom: 4px; }
.pill { display: inline-block; font-size: .78rem; font-weight: 600; padding: 2px 9px; border-radius: 99px; background: var(--accent-soft); color: var(--accent); }
.pill.hard { background: var(--warn-soft); color: var(--warn); }
.pill.multi { background: var(--surface-2); color: var(--muted); }
.objective { margin: 18px 0; }
.objective h3 { display: flex; gap: 10px; }
.objective h3 .num { color: var(--muted); font-variant-numeric: tabular-nums; flex: none; }
.objective .modules { font-size: .82rem; color: var(--muted); margin: -4px 0 10px; }
.objective p { margin: 0 0 10px; }
.facts, .traps { margin: 10px 0 0; padding: 12px 14px 12px 32px; border-radius: 10px; }
.facts { background: var(--surface-2); }
.traps { background: var(--warn-soft); }
.facts li, .traps li { margin: 4px 0; }
.block-label { font-size: .75rem; text-transform: uppercase; letter-spacing: .08em; font-weight: 700; color: var(--muted); margin: 14px 0 6px; }
.traps-label { color: var(--warn); }
.table-wrap { overflow-x: auto; margin: 12px 0 0; border: 1px solid var(--border); border-radius: 10px; }
table { border-collapse: collapse; width: 100%; font-size: .92rem; }
th, td { text-align: left; padding: 8px 12px; border-bottom: 1px solid var(--border); vertical-align: top; }
th { background: var(--surface-2); font-weight: 600; }
tr:last-child td { border-bottom: 0; }
.domain-foot { display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap; margin-top: 20px; }

/* Buttons */
.btn { display: inline-flex; align-items: center; gap: 6px; border: 1px solid var(--border); background: var(--surface); color: var(--text); font: 600 .95rem var(--font); padding: 9px 16px; border-radius: 9px; cursor: pointer; }
.btn:hover { background: var(--surface-2); text-decoration: none; }
.btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
:root[data-theme="dark"] .btn.primary { color: #0d1220; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .btn.primary { color: #0d1220; } }
.btn.primary:hover { filter: brightness(1.05); }
.btn:disabled { opacity: .5; cursor: not-allowed; }
.btn-row { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }

/* Practice sets */
.set-card { display: flex; flex-direction: column; gap: 6px; }
.set-card h3 { margin: 0; }
.set-card .meta { color: var(--muted); font-size: .88rem; }
.set-card .btn-row { margin-top: auto; padding-top: 10px; }
.score-badge { font-size: .82rem; font-weight: 600; color: var(--good); }

/* Quiz */
.quiz-head { display: flex; justify-content: space-between; align-items: center; gap: 12px; flex-wrap: wrap; margin-bottom: 14px; }
.progress { height: 6px; background: var(--surface-2); border-radius: 99px; overflow: hidden; margin: 8px 0 18px; }
.progress > i { display: block; height: 100%; background: var(--accent); transition: width .2s; }
.timer { font: 600 1.05rem var(--mono); padding: 4px 10px; border-radius: 8px; background: var(--surface-2); }
.timer.low { background: var(--bad-soft); color: var(--bad); }
.question { max-width: 820px; }
.question .q-meta { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 10px; font-size: .85rem; color: var(--muted); align-items: center; }
.question .stem { font-size: 1.08rem; font-weight: 500; margin: 0 0 16px; }
.options { display: grid; gap: 10px; margin: 0; padding: 0; list-style: none; }
.option { display: flex; gap: 12px; align-items: flex-start; padding: 12px 14px; border: 1.5px solid var(--border); border-radius: 10px; background: var(--surface); cursor: pointer; transition: border-color .12s, background .12s; }
.option:hover { border-color: var(--accent); }
.option input { margin-top: 4px; accent-color: var(--accent); flex: none; }
.option .letter { font-weight: 700; color: var(--muted); flex: none; width: 1.2em; }
.option.selected { border-color: var(--accent); background: var(--accent-soft); }
.option.correct { border-color: var(--good); background: var(--good-soft); }
.option.wrong { border-color: var(--bad); background: var(--bad-soft); }
.option.locked { cursor: default; }
.explain { margin-top: 16px; padding: 14px 16px; border-radius: 10px; border-left: 4px solid var(--good); background: var(--surface); border-top: 1px solid var(--border); border-right: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.explain.wrong { border-left-color: var(--bad); }
.explain h4 { margin: 0 0 6px; }
.quiz-nav { display: flex; justify-content: space-between; gap: 10px; margin-top: 22px; flex-wrap: wrap; }
.palette { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 22px; }
.palette button { width: 34px; height: 34px; border-radius: 8px; border: 1px solid var(--border); background: var(--surface); color: var(--text); font: 600 .8rem var(--font); cursor: pointer; }
.palette button.answered { background: var(--accent-soft); border-color: var(--accent); color: var(--accent); }
.palette button.flagged { box-shadow: inset 0 -3px 0 var(--warn); }
.palette button.current { outline: 2px solid var(--text); outline-offset: 1px; }
.palette button.ok { background: var(--good-soft); border-color: var(--good); color: var(--good); }
.palette button.no { background: var(--bad-soft); border-color: var(--bad); color: var(--bad); }

/* Results */
.result-hero { text-align: center; padding: 28px 20px; }
.result-hero .big { font-size: 3rem; font-weight: 700; letter-spacing: -.03em; }
.result-hero .verdict { font-weight: 700; font-size: 1.1rem; }
.verdict.pass { color: var(--good); }
.verdict.fail { color: var(--bad); }
.breakdown .weight-row { grid-template-columns: minmax(150px, 220px) 1fr 70px; }
.bar.good > i { background: var(--good); }
.bar.mid > i { background: var(--warn); }
.bar.bad > i { background: var(--bad); }
.review-item { margin: 14px 0; }
.review-item summary { cursor: pointer; font-weight: 500; }
.review-item summary::marker { color: var(--muted); }
.tag-ok { color: var(--good); font-weight: 700; }
.tag-no { color: var(--bad); font-weight: 700; }

.footer { max-width: 1180px; margin: 0 auto; padding: 24px 16px 40px; color: var(--muted); font-size: .82rem; border-top: 1px solid var(--border); }
.callout { padding: 14px 16px; border-radius: 10px; background: var(--accent-soft); color: var(--text); }
.empty { color: var(--muted); padding: 24px; text-align: center; }
.question .stem.scenario { font-weight: 400; margin-bottom: 10px; }