:root {
  color-scheme: light dark;
  --fg: #1a1a1a;
  --bg: #fdfdfd;
  --card: #ffffff;
  --line: #e2e2e2;
  --accent: #f38020;
  --ok: #1a7f37;
  --bad: #c1121f;
}

@media (prefers-color-scheme: dark) {
  :root {
    --fg: #ececec;
    --bg: #16181d;
    --card: #1f2229;
    --line: #333842;
    --ok: #4ac26b;
    --bad: #ff6b6b;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  padding: 2rem 1rem;
  font-family: -apple-system, "Noto Sans TC", "Microsoft JhengHei", sans-serif;
  line-height: 1.7;
  color: var(--fg);
  background: var(--bg);
}

.wrap {
  max-width: 40rem;
  margin: 0 auto;
}

h1 {
  font-size: 1.6rem;
  margin: 0 0 .3rem;
}

.hint {
  margin: 0 0 1.5rem;
  font-size: .9rem;
  opacity: .7;
}

.status {
  padding: .8rem 1rem;
  border: 1px solid var(--line);
  border-radius: .5rem;
  background: var(--card);
  font-size: .9rem;
}

.status.error {
  border-color: var(--bad);
  color: var(--bad);
}

fieldset {
  margin: 0 0 1rem;
  padding: 1rem 1.2rem;
  border: 1px solid var(--line);
  border-radius: .5rem;
  background: var(--card);
}

legend {
  padding: 0 .4rem;
  font-weight: 600;
}

label {
  display: block;
  padding: .35rem 0;
  cursor: pointer;
}

input[type="radio"] {
  margin-right: .5rem;
  accent-color: var(--accent);
}

button {
  padding: .7rem 1.6rem;
  border: 0;
  border-radius: .5rem;
  background: var(--accent);
  color: #fff;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
}

button:disabled {
  opacity: .5;
  cursor: not-allowed;
}

.result {
  margin-top: 1.5rem;
  padding: 1rem 1.2rem;
  border: 1px solid var(--line);
  border-radius: .5rem;
  background: var(--card);
}

.score {
  font-size: 1.3rem;
  font-weight: 700;
  margin: 0 0 .6rem;
}

.result ul {
  margin: 0;
  padding-left: 1.2rem;
}

.correct { color: var(--ok); }
.wrong { color: var(--bad); }