:root {
  color-scheme: light dark;
  --bg: #f6f7fb;
  --card: #ffffff;
  --text: #1b1f27;
  --muted: #6b7280;
  --border: #e3e5ea;
  --accent: #2f5fd0;
  --accent-fg: #ffffff;
  --good: #1a8a4a;
  --bad: #d1373f;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #14161c;
    --card: #1e212a;
    --text: #eceef2;
    --muted: #9aa0ab;
    --border: #2c3038;
    --accent: #6d93ff;
    --accent-fg: #0c1220;
    --good: #4ad183;
    --bad: #ff6b73;
  }
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: "PingFang TC", "Microsoft JhengHei", "Noto Sans TC", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}
.topbar {
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--border);
  background: var(--card);
}
.topbar h1 {
  margin: 0;
  font-size: 1.15rem;
  cursor: pointer;
}
main {
  flex: 1;
  width: 100%;
  max-width: 780px;
  margin: 0 auto;
  padding: 1.25rem;
}
.footer {
  text-align: center;
  font-size: 0.75rem;
  color: var(--muted);
  padding: 1rem;
  border-top: 1px solid var(--border);
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1rem 1.25rem;
  margin-bottom: 0.9rem;
}
.grid {
  display: grid;
  gap: 0.75rem;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
}
.pick-btn {
  display: block;
  width: 100%;
  text-align: left;
  padding: 0.85rem 1rem;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--text);
  font-size: 0.95rem;
  cursor: pointer;
}
.pick-btn:hover { border-color: var(--accent); }
.pick-btn .sub {
  display: block;
  color: var(--muted);
  font-size: 0.8rem;
  margin-top: 0.2rem;
}
.pick-btn.warn { opacity: 0.55; }

.breadcrumb {
  color: var(--muted);
  font-size: 0.85rem;
  margin-bottom: 0.75rem;
}
.breadcrumb a { color: var(--accent); cursor: pointer; text-decoration: none; }

h2 { font-size: 1.05rem; margin: 0 0 0.75rem; }

.q-progress {
  font-size: 0.85rem;
  color: var(--muted);
  margin-bottom: 0.5rem;
}
.q-text {
  font-size: 1.05rem;
  line-height: 1.6;
  margin-bottom: 1rem;
  white-space: pre-wrap;
}
.opt {
  display: flex;
  gap: 0.6rem;
  align-items: flex-start;
  width: 100%;
  text-align: left;
  padding: 0.7rem 0.85rem;
  margin-bottom: 0.55rem;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text);
  cursor: pointer;
  font-size: 0.95rem;
  line-height: 1.5;
}
.opt .tag {
  flex: none;
  font-weight: 600;
  color: var(--muted);
}
.opt:hover { border-color: var(--accent); }
.opt.selected { border-color: var(--accent); box-shadow: inset 0 0 0 1px var(--accent); }
.opt.correct { border-color: var(--good); box-shadow: inset 0 0 0 1px var(--good); background: color-mix(in srgb, var(--good) 12%, var(--bg)); }
.opt.wrong { border-color: var(--bad); box-shadow: inset 0 0 0 1px var(--bad); background: color-mix(in srgb, var(--bad) 12%, var(--bg)); }
.opt:disabled { cursor: default; }

.nav-row {
  display: flex;
  justify-content: space-between;
  gap: 0.6rem;
  margin-top: 1rem;
}
button.primary, button.secondary {
  padding: 0.6rem 1.1rem;
  border-radius: 8px;
  border: none;
  font-size: 0.9rem;
  cursor: pointer;
}
button.primary { background: var(--accent); color: var(--accent-fg); }
button.secondary { background: transparent; border: 1px solid var(--border); color: var(--text); }
button:disabled { opacity: 0.4; cursor: default; }

.score-hero {
  text-align: center;
  padding: 1.5rem 1rem;
}
.score-hero .big { font-size: 2.4rem; font-weight: 700; }

.review-item.correct { border-left: 4px solid var(--good); }
.review-item.wrong { border-left: 4px solid var(--bad); }
.review-item .opt { pointer-events: none; }

.badge {
  display: inline-block;
  font-size: 0.72rem;
  padding: 0.15rem 0.5rem;
  border-radius: 999px;
  background: var(--border);
  color: var(--muted);
  margin-left: 0.4rem;
}