:root {
  --surface-1: #fcfcfb;
  --page: #f9f9f7;
  --text-primary: #0b0b0b;
  --text-secondary: #52514e;
  --muted: #898781;
  --gridline: #e1e0d9;
  --border: rgba(11, 11, 11, 0.1);
  --seq-100: #cde2fb;
  --seq-300: #6da7ec;
  --seq-450: #2a78d6;
  --seq-600: #184f95;
  --good: #0ca30c;
  --good-text: #006300;
  --critical: #d03b3b;
  --warning: #eda100;
}

@media (prefers-color-scheme: dark) {
  :root {
    --surface-1: #1a1a19;
    --page: #0d0d0d;
    --text-primary: #ffffff;
    --text-secondary: #c3c2b7;
    --muted: #898781;
    --gridline: #2c2c2a;
    --border: rgba(255, 255, 255, 0.1);
    --seq-100: #184f95;
    --seq-300: #256abf;
    --seq-450: #3987e5;
    --seq-600: #86b6ef;
    --good: #0ca30c;
    --good-text: #0ca30c;
    --critical: #e66767;
    --warning: #c98500;
  }
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: system-ui, -apple-system, "Segoe UI", sans-serif;
  background: var(--page);
  color: var(--text-primary);
}

.wrap {
  max-width: 720px;
  margin: 0 auto;
  padding: 20px 16px 80px;
}

header h1 {
  font-size: 1.15rem;
  margin: 0 0 2px;
}

header .sub {
  color: var(--text-secondary);
  font-size: 0.85rem;
  margin-bottom: 16px;
}

.countdown {
  display: inline-flex;
  align-items: baseline;
  gap: 6px;
  background: var(--surface-1);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 8px 14px;
  margin-bottom: 16px;
}

.countdown .num {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--seq-450);
}

.countdown .label {
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.stat-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px;
  margin-bottom: 18px;
}

.stat-tile {
  background: var(--surface-1);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px 14px;
}

.stat-tile .value {
  font-size: 1.5rem;
  font-weight: 700;
}

.stat-tile .label {
  font-size: 0.75rem;
  color: var(--text-secondary);
  margin-bottom: 4px;
}

.topic-bars {
  background: var(--surface-1);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px 16px;
  margin-bottom: 20px;
}

.topic-bars h2 {
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin: 0 0 10px;
  font-weight: 600;
}

.topic-row {
  display: grid;
  grid-template-columns: 6.5em 1fr 3.2em;
  align-items: center;
  gap: 8px;
  font-size: 0.8rem;
  margin-bottom: 8px;
}

.topic-row .name {
  color: var(--text-primary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.topic-row .pct {
  color: var(--text-secondary);
  text-align: right;
  font-variant-numeric: tabular-nums;
}

.bar-track {
  background: var(--gridline);
  border-radius: 4px;
  height: 8px;
  overflow: hidden;
}

.bar-fill {
  background: var(--seq-450);
  height: 100%;
  border-radius: 4px;
}

.mode-row {
  display: flex;
  gap: 8px;
  margin-bottom: 16px;
}

.mode-btn {
  flex: 1;
  padding: 8px 10px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--surface-1);
  color: var(--text-secondary);
  font-size: 0.8rem;
  cursor: pointer;
}

.mode-btn.active {
  border-color: var(--seq-450);
  color: var(--seq-450);
  font-weight: 600;
}

.card {
  background: var(--surface-1);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 18px;
}

.tag {
  display: inline-block;
  font-size: 0.72rem;
  color: var(--seq-450);
  background: color-mix(in srgb, var(--seq-450) 12%, transparent);
  padding: 3px 8px;
  border-radius: 999px;
  margin-bottom: 10px;
}

.q-text {
  font-size: 1rem;
  line-height: 1.6;
  margin-bottom: 16px;
}

.choice {
  display: block;
  width: 100%;
  text-align: left;
  padding: 12px 14px;
  margin-bottom: 8px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--page);
  color: var(--text-primary);
  font-size: 0.9rem;
  line-height: 1.5;
  cursor: pointer;
}

.choice:hover:not(:disabled) {
  border-color: var(--seq-450);
}

.choice:disabled {
  cursor: default;
}

.choice.correct {
  border-color: var(--good);
  background: color-mix(in srgb, var(--good) 12%, var(--page));
}

.choice.wrong {
  border-color: var(--critical);
  background: color-mix(in srgb, var(--critical) 12%, var(--page));
}

.choice.selected {
  border-color: var(--seq-450);
  background: color-mix(in srgb, var(--seq-450) 10%, var(--page));
}

.feedback {
  margin-top: 14px;
  padding: 12px 14px;
  border-radius: 8px;
  font-size: 0.85rem;
  line-height: 1.6;
}

.feedback.good {
  background: color-mix(in srgb, var(--good) 10%, var(--page));
  color: var(--good-text);
}

.feedback.bad {
  background: color-mix(in srgb, var(--critical) 10%, var(--page));
  color: var(--critical);
}

.feedback .explain {
  color: var(--text-primary);
  margin-top: 8px;
}

.next-btn {
  margin-top: 14px;
  width: 100%;
  padding: 12px;
  border-radius: 8px;
  border: none;
  background: var(--seq-450);
  color: #fff;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
}

.empty {
  text-align: center;
  color: var(--text-secondary);
  padding: 30px 10px;
  font-size: 0.9rem;
}

.choice-num {
  font-weight: 700;
  color: var(--text-secondary);
  margin-right: 8px;
}

.top-tabs {
  display: flex;
  gap: 8px;
  margin-bottom: 16px;
}

.tab-btn {
  flex: 1;
  padding: 10px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--surface-1);
  color: var(--text-secondary);
  font-size: 0.85rem;
  cursor: pointer;
}

.tab-btn.active {
  border-color: var(--seq-450);
  color: var(--seq-450);
  font-weight: 600;
}

.exam-start {
  background: var(--surface-1);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 22px 18px;
  text-align: center;
}

.exam-start .big-num {
  font-size: 2rem;
  font-weight: 700;
  color: var(--seq-450);
  margin: 4px 0;
}

.start-btn {
  margin-top: 16px;
  width: 100%;
  padding: 14px;
  border-radius: 8px;
  border: none;
  background: var(--seq-450);
  color: #fff;
  font-weight: 700;
  font-size: 1rem;
  cursor: pointer;
}

.exam-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 12px;
}

.progress-label {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.timer {
  font-size: 1.3rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  color: var(--seq-450);
}

.timer.warn {
  color: var(--warning);
}

.timer.critical {
  color: var(--critical);
}

.nav-grid {
  display: grid;
  grid-template-columns: repeat(10, 1fr);
  gap: 5px;
  margin-bottom: 14px;
}

@media (max-width: 480px) {
  .nav-grid {
    grid-template-columns: repeat(6, 1fr);
    gap: 6px;
  }
}

.nav-cell {
  aspect-ratio: 1;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: var(--page);
  color: var(--text-secondary);
  font-size: 0.75rem;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  font-variant-numeric: tabular-nums;
}

.nav-cell.answered {
  background: color-mix(in srgb, var(--seq-450) 15%, var(--page));
  border-color: var(--seq-450);
  color: var(--seq-450);
}

.nav-cell.current {
  border-width: 2px;
  border-color: var(--text-primary);
  font-weight: 700;
}

.exam-actions {
  display: flex;
  gap: 8px;
  margin-top: 14px;
}

.exam-actions button {
  flex: 1;
  padding: 12px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--surface-1);
  color: var(--text-primary);
  font-size: 0.85rem;
  cursor: pointer;
}

.exam-actions .finish-btn {
  background: var(--seq-450);
  color: #fff;
  border: none;
  font-weight: 700;
}

.result-banner {
  border-radius: 10px;
  padding: 18px;
  margin-bottom: 18px;
}

.result-banner.pass {
  background: color-mix(in srgb, var(--good) 12%, var(--page));
}

.result-banner.warn {
  background: color-mix(in srgb, var(--warning) 18%, var(--page));
}

.result-banner.fail {
  background: color-mix(in srgb, var(--critical) 12%, var(--page));
}

.result-banner .score {
  font-size: 2rem;
  font-weight: 700;
}

.result-banner .msg {
  font-size: 0.9rem;
  margin-top: 4px;
  font-weight: 600;
}

.result-banner .note {
  font-size: 0.75rem;
  color: var(--text-secondary);
  margin-top: 10px;
  line-height: 1.5;
}

.review-item {
  border-bottom: 1px solid var(--gridline);
  padding: 14px 0;
}

.review-item:last-child {
  border-bottom: none;
}

.review-item .rtag {
  font-size: 0.7rem;
  color: var(--seq-450);
  margin-bottom: 4px;
}

.review-item .rq {
  font-size: 0.9rem;
  margin-bottom: 8px;
  line-height: 1.6;
}

.review-item .ans-line {
  font-size: 0.82rem;
  margin-bottom: 3px;
}

.review-item .ans-line.correct-mark {
  color: var(--good-text);
}

.review-item .ans-line.wrong-mark {
  color: var(--critical);
}

.review-item .rexplain {
  font-size: 0.8rem;
  color: var(--text-secondary);
  margin-top: 8px;
  line-height: 1.6;
}

.retry-row {
  display: flex;
  gap: 8px;
  margin-top: 18px;
}

.retry-row button {
  flex: 1;
  padding: 12px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--surface-1);
  color: var(--text-primary);
  cursor: pointer;
  font-size: 0.85rem;
}

.retry-row .primary {
  background: var(--seq-450);
  color: #fff;
  border: none;
  font-weight: 700;
}