:root {
  color-scheme: light;
  --bg: #f6f8ff;
  --card: #ffffff;
  --text: #1f2330;
  --subtle: #6e768a;
  --primary: #4f7cff;
  --primary-hover: #3e67df;
  --success: #13a96b;
  --danger: #da3e52;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Noto Sans TC",
    "PingFang TC", sans-serif;
  background: radial-gradient(circle at top, #ecf1ff 0%, var(--bg) 50%);
  color: var(--text);
  min-height: 100vh;
}

.container {
  width: min(760px, 92vw);
  margin: 40px auto;
}

.hero {
  margin-bottom: 20px;
}

.hero h1 {
  margin: 0 0 8px 0;
  font-size: 2rem;
}

.hero p {
  margin: 0;
  color: var(--subtle);
}

.card {
  background: var(--card);
  border-radius: 16px;
  padding: 24px;
  box-shadow: 0 10px 30px rgba(35, 47, 84, 0.08);
}

.hidden {
  display: none;
}

.progress {
  color: var(--subtle);
  font-size: 0.95rem;
  margin-bottom: 10px;
}

#question-text {
  margin: 0 0 18px 0;
  line-height: 1.5;
}

.choices {
  display: grid;
  gap: 10px;
}

.choice-btn {
  width: 100%;
  text-align: left;
  border: 1px solid #d8deef;
  border-radius: 12px;
  background: #fff;
  color: var(--text);
  padding: 14px 16px;
  font-size: 1rem;
  cursor: pointer;
  transition: all 0.2s ease;
}

.choice-btn:hover {
  border-color: var(--primary);
  transform: translateY(-1px);
}

.choice-btn.selected {
  border-color: var(--primary);
  background: rgba(79, 124, 255, 0.08);
}

.choice-btn.correct {
  border-color: var(--success);
  background: rgba(19, 169, 107, 0.1);
}

.choice-btn.wrong {
  border-color: var(--danger);
  background: rgba(218, 62, 82, 0.1);
}

.actions {
  margin-top: 18px;
  display: flex;
  justify-content: flex-end;
}

button {
  border: none;
  border-radius: 10px;
  padding: 10px 16px;
  font-size: 1rem;
  cursor: pointer;
  transition: background 0.2s ease;
}

#next-btn,
#restart-btn {
  background: var(--primary);
  color: #fff;
}

#next-btn:hover,
#restart-btn:hover {
  background: var(--primary-hover);
}

#next-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

#score-text {
  font-size: 1.4rem;
  margin-bottom: 8px;
}

#summary-text {
  color: var(--subtle);
  margin-bottom: 16px;
}

@media (max-width: 600px) {
  .container {
    margin: 20px auto;
  }

  .card {
    padding: 18px;
  }

  .hero h1 {
    font-size: 1.7rem;
  }
}