:root {
  --bg: #f4f6fa;
  --surface: #ffffff;
  --surface-2: #eef1f6;
  --border: #d9dee8;
  --text: #1b2230;
  --muted: #5d6779;
  --primary: #2f5bd3;
  --primary-ink: #ffffff;
  --primary-soft: #e3eafc;
  --accent: #c2410c;
  --ok: #157a3c;
  --ok-soft: #e1f4e8;
  --bad: #b42318;
  --bad-soft: #fde7e5;
  --warn-soft: #fff4d6;
  --code-bg: #10151f;
  --code-text: #e6ebf5;
  --shadow: 0 1px 2px rgba(16, 24, 40, .06), 0 4px 16px rgba(16, 24, 40, .06);
  --radius: 14px;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0e121a;
    --surface: #161c27;
    --surface-2: #1d2532;
    --border: #2a3444;
    --text: #e6ebf5;
    --muted: #97a3b8;
    --primary: #6d8ff0;
    --primary-ink: #0b1020;
    --primary-soft: #1f2b4a;
    --accent: #f08a4b;
    --ok: #4cc27a;
    --ok-soft: #133524;
    --bad: #f07067;
    --bad-soft: #3d1a19;
    --warn-soft: #3a3016;
    --code-bg: #0a0d14;
    --shadow: 0 1px 2px rgba(0, 0, 0, .3), 0 4px 16px rgba(0, 0, 0, .25);
    color-scheme: dark;
  }
}

:root[data-theme="dark"] {
  --bg: #0e121a;
  --surface: #161c27;
  --surface-2: #1d2532;
  --border: #2a3444;
  --text: #e6ebf5;
  --muted: #97a3b8;
  --primary: #6d8ff0;
  --primary-ink: #0b1020;
  --primary-soft: #1f2b4a;
  --accent: #f08a4b;
  --ok: #4cc27a;
  --ok-soft: #133524;
  --bad: #f07067;
  --bad-soft: #3d1a19;
  --warn-soft: #3a3016;
  --code-bg: #0a0d14;
  --shadow: 0 1px 2px rgba(0, 0, 0, .3), 0 4px 16px rgba(0, 0, 0, .25);
  color-scheme: dark;
}

* { box-sizing: border-box; }

html, body { margin: 0; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.55;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

[hidden] { display: none !important; }

h1, h2 { line-height: 1.25; margin: 0 0 .5rem; }
h1 { font-size: 1.75rem; }
h2 { font-size: 1.15rem; }

.muted { color: var(--muted); }

.container {
  width: 100%;
  max-width: 860px;
  margin: 0 auto;
  padding: 16px;
  flex: 1;
}

/* ---------- Topbar ---------- */
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 16px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 10;
}
.brand {
  display: flex;
  align-items: center;
  gap: .6rem;
  font-weight: 700;
  color: var(--text);
  text-decoration: none;
}
.brand-mark {
  display: grid;
  place-items: center;
  width: 30px;
  height: 30px;
  border-radius: 8px;
  background: var(--primary);
  color: var(--primary-ink);
}
.icon-btn {
  border: 1px solid var(--border);
  background: var(--surface-2);
  color: var(--text);
  width: 38px;
  height: 38px;
  border-radius: 10px;
  font-size: 1.1rem;
  cursor: pointer;
}

/* ---------- Cards ---------- */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 20px;
  margin-bottom: 16px;
}
.card-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: .5rem;
}
.card-head h2 { margin: 0; }

.hero { margin: 12px 0 20px; }

/* ---------- Setup form ---------- */
fieldset { border: 0; padding: 0; margin: 0 0 20px; min-width: 0; }
legend { font-weight: 700; margin-bottom: 8px; padding: 0; }

.seg {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px;
}
.seg-3 { grid-template-columns: repeat(3, 1fr); }
.seg-item { position: relative; cursor: pointer; }
.seg-item input { position: absolute; opacity: 0; pointer-events: none; }
.seg-item span {
  display: flex;
  flex-direction: column;
  gap: 2px;
  height: 100%;
  padding: 12px 14px;
  border: 1.5px solid var(--border);
  border-radius: 12px;
  background: var(--surface-2);
  transition: border-color .15s, background .15s;
}
.seg-item small { color: var(--muted); font-size: .82rem; line-height: 1.35; }
.seg-item input:checked + span {
  border-color: var(--primary);
  background: var(--primary-soft);
}
.seg-item input:focus-visible + span { outline: 2px solid var(--primary); outline-offset: 2px; }

.checks {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px;
}
.check {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 14px;
  border: 1.5px solid var(--border);
  border-radius: 12px;
  background: var(--surface-2);
  cursor: pointer;
}
.check:has(input:checked) { border-color: var(--primary); background: var(--primary-soft); }
.check input { width: 18px; height: 18px; accent-color: var(--primary); flex-shrink: 0; }
.check .count { margin-left: auto; color: var(--muted); font-size: .85rem; white-space: nowrap; }

.row {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  align-items: flex-end;
  margin-bottom: 20px;
}
.field { display: flex; flex-direction: column; gap: 4px; font-size: .9rem; color: var(--muted); }
.field select {
  font: inherit;
  color: var(--text);
  background: var(--surface-2);
  border: 1.5px solid var(--border);
  border-radius: 10px;
  padding: 8px 10px;
  min-width: 160px;
}
.toggle { display: inline-flex; align-items: center; gap: 8px; cursor: pointer; padding-bottom: 8px; }
.toggle input { width: 18px; height: 18px; accent-color: var(--primary); }

.error {
  color: var(--bad);
  background: var(--bad-soft);
  padding: 10px 14px;
  border-radius: 10px;
}

/* ---------- Buttons ---------- */
.btn {
  font: inherit;
  font-weight: 600;
  border: 1.5px solid var(--border);
  background: var(--surface);
  color: var(--text);
  padding: 9px 16px;
  border-radius: 10px;
  cursor: pointer;
  transition: filter .15s, background .15s;
}
.btn:hover { filter: brightness(.97); }
.btn:disabled { opacity: .45; cursor: not-allowed; }
.btn-primary { background: var(--primary); border-color: var(--primary); color: var(--primary-ink); }
.btn-accent { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn-ghost { background: transparent; }
.btn-sm { padding: 5px 10px; font-size: .85rem; }
.btn-lg { padding: 12px 28px; font-size: 1.05rem; width: 100%; }

/* ---------- History ---------- */
.history-table { width: 100%; border-collapse: collapse; font-size: .92rem; }
.history-table th, .history-table td {
  text-align: left;
  padding: 8px 6px;
  border-bottom: 1px solid var(--border);
}
.history-table th { color: var(--muted); font-weight: 600; }
.history-table td.num { font-variant-numeric: tabular-nums; }
.badge {
  display: inline-block;
  padding: 1px 8px;
  border-radius: 999px;
  font-size: .8rem;
  font-weight: 600;
}
.badge-ok { background: var(--ok-soft); color: var(--ok); }
.badge-bad { background: var(--bad-soft); color: var(--bad); }
.badge-mid { background: var(--warn-soft); color: var(--text); }

/* ---------- Quiz ---------- */
.quiz-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 8px;
}
.quiz-meta { display: flex; gap: 6px; flex-wrap: wrap; }
.pill {
  padding: 3px 12px;
  border-radius: 999px;
  background: var(--primary);
  color: var(--primary-ink);
  font-weight: 600;
  font-size: .85rem;
}
.pill-soft { background: var(--surface-2); color: var(--text); border: 1px solid var(--border); }
.timer {
  font-variant-numeric: tabular-nums;
  font-weight: 700;
  padding: 3px 12px;
  border-radius: 999px;
  background: var(--surface-2);
  border: 1px solid var(--border);
}
.timer.low { background: var(--bad-soft); color: var(--bad); border-color: var(--bad); }

.progress {
  height: 6px;
  border-radius: 999px;
  background: var(--surface-2);
  overflow: hidden;
  margin-bottom: 16px;
}
.progress-bar { height: 100%; width: 0; background: var(--primary); transition: width .25s; }

.q-tags { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 10px; }
.tag {
  font-size: .78rem;
  font-weight: 600;
  padding: 2px 10px;
  border-radius: 6px;
  background: var(--primary-soft);
  color: var(--primary);
}
.tag-soft { background: var(--surface-2); color: var(--muted); }
.tag-hint { background: var(--warn-soft); color: var(--text); }

.q-text { font-size: 1.12rem; font-weight: 600; margin-bottom: 14px; white-space: pre-line; }

.code {
  background: var(--code-bg);
  color: var(--code-text);
  padding: 14px 16px;
  border-radius: 10px;
  overflow-x: auto;
  font-family: ui-monospace, "Cascadia Code", "JetBrains Mono", Consolas, monospace;
  font-size: .88rem;
  line-height: 1.5;
  margin: 0 0 16px;
  tab-size: 4;
}
.code code { font-family: inherit; white-space: pre; }
.code .k { color: #8fb4ff; }
.code .s { color: #a6e3a1; }
.code .c { color: #7f8aa3; font-style: italic; }
.code .n { color: #f5c07a; }

.options { display: flex; flex-direction: column; gap: 10px; }
.option {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 12px 14px;
  border: 1.5px solid var(--border);
  border-radius: 12px;
  background: var(--surface-2);
  cursor: pointer;
  transition: border-color .12s, background .12s;
}
.option:hover { border-color: var(--primary); }
.option input { margin-top: 3px; width: 18px; height: 18px; accent-color: var(--primary); flex-shrink: 0; }
.option .key {
  flex-shrink: 0;
  width: 24px;
  height: 24px;
  display: grid;
  place-items: center;
  border-radius: 6px;
  background: var(--surface);
  border: 1px solid var(--border);
  font-size: .8rem;
  font-weight: 700;
  color: var(--muted);
}
.option .txt { flex: 1; overflow-wrap: anywhere; }
.option.selected { border-color: var(--primary); background: var(--primary-soft); }
.option.correct { border-color: var(--ok); background: var(--ok-soft); }
.option.wrong { border-color: var(--bad); background: var(--bad-soft); }
.option.missed { border-color: var(--ok); border-style: dashed; }
.options.locked .option { cursor: default; }
.options.locked .option:hover { border-color: inherit; }
.options.locked .option.correct:hover { border-color: var(--ok); }
.options.locked .option.wrong:hover { border-color: var(--bad); }
.option code, .q-text code, .feedback code {
  font-family: ui-monospace, Consolas, monospace;
  font-size: .9em;
  background: var(--surface);
  padding: 0 4px;
  border-radius: 4px;
}

.feedback {
  margin-top: 16px;
  padding: 14px 16px;
  border-radius: 12px;
  border-left: 4px solid var(--ok);
  background: var(--ok-soft);
}
.feedback.bad { border-left-color: var(--bad); background: var(--bad-soft); }
.feedback strong { display: block; margin-bottom: 4px; }

.quiz-actions {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  align-items: center;
  margin-bottom: 16px;
}
.spacer { flex: 1; }

.qmap-card summary { cursor: pointer; font-weight: 600; }
.qmap {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(38px, 1fr));
  gap: 6px;
  margin-top: 12px;
}
.qmap button {
  font: inherit;
  font-size: .85rem;
  padding: 6px 0;
  border-radius: 8px;
  border: 1.5px solid var(--border);
  background: var(--surface-2);
  color: var(--text);
  cursor: pointer;
}
.qmap button.answered { background: var(--primary-soft); border-color: var(--primary); }
.qmap button.ok { background: var(--ok-soft); border-color: var(--ok); }
.qmap button.bad { background: var(--bad-soft); border-color: var(--bad); }
.qmap button.current { outline: 2px solid var(--text); outline-offset: 1px; }

.kbd-hint { font-size: .82rem; text-align: center; }
kbd {
  font-family: ui-monospace, Consolas, monospace;
  font-size: .78rem;
  padding: 1px 6px;
  border: 1px solid var(--border);
  border-bottom-width: 2px;
  border-radius: 5px;
  background: var(--surface);
}

/* ---------- Result ---------- */
.result-hero { display: flex; gap: 24px; align-items: center; flex-wrap: wrap; }
.score-ring {
  --p: 0;
  --c: var(--primary);
  width: 120px;
  height: 120px;
  border-radius: 50%;
  background: conic-gradient(var(--c) calc(var(--p) * 1%), var(--surface-2) 0);
  display: grid;
  place-items: center;
  flex-shrink: 0;
}
.score-ring span {
  width: 92px;
  height: 92px;
  border-radius: 50%;
  background: var(--surface);
  display: grid;
  place-items: center;
  font-size: 1.6rem;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
}
.result-actions { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 12px; }

.breakdown { display: flex; flex-direction: column; gap: 10px; }
.bd-row { display: grid; grid-template-columns: minmax(120px, 220px) 1fr 70px; gap: 12px; align-items: center; font-size: .92rem; }
.bd-bar { height: 10px; border-radius: 999px; background: var(--surface-2); overflow: hidden; }
.bd-bar > div { height: 100%; background: var(--primary); }
.bd-val { text-align: right; font-variant-numeric: tabular-nums; color: var(--muted); }

.review { display: flex; flex-direction: column; gap: 14px; }
.review-item {
  border: 1px solid var(--border);
  border-left: 4px solid var(--ok);
  border-radius: 12px;
  padding: 14px 16px;
}
.review-item.bad { border-left-color: var(--bad); }
.review-item .q-text { font-size: 1rem; }
.review-item .options .option { padding: 8px 12px; cursor: default; }
.review-item .exp { margin-top: 10px; font-size: .92rem; color: var(--muted); }

.footer { text-align: center; padding: 20px 16px; font-size: .82rem; }

/* ---------- Responsive ---------- */
@media (max-width: 640px) {
  h1 { font-size: 1.4rem; }
  .card { padding: 16px; }
  .seg, .seg-3, .checks { grid-template-columns: 1fr; }
  .field select { min-width: 0; width: 100%; }
  .row .field { flex: 1 1 140px; }
  .quiz-actions .btn { flex: 1 1 auto; }
  .quiz-actions .spacer { display: none; }
  .bd-row { grid-template-columns: 1fr 60px; }
  .bd-row .bd-bar { grid-column: 1 / -1; grid-row: 2; }
  .history-table .hide-sm { display: none; }
}