:root {
  color-scheme: light dark;
  --bg: #f5f6f8;
  --card-bg: #ffffff;
  --text: #1a1a1a;
  --muted: #666666;
  --border: #dddddd;
  --accent: #2563eb;
  --correct: #16a34a;
  --incorrect: #dc2626;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #17181c;
    --card-bg: #24262c;
    --text: #f0f0f0;
    --muted: #a0a0a8;
    --border: #3a3c44;
  }
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  line-height: 1.5;
}

#app {
  max-width: 640px;
  margin: 0 auto;
  padding: 24px 16px 64px;
}

.card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
}

h1 {
  font-size: 1.3rem;
  margin-top: 0;
}

form {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

input[type="text"] {
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: transparent;
  color: var(--text);
  font-size: 1rem;
}

button {
  padding: 10px 16px;
  border: none;
  border-radius: 8px;
  background: var(--accent);
  color: white;
  font-size: 1rem;
  cursor: pointer;
}

button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.nav {
  display: flex;
  gap: 8px;
  margin: 16px 0;
}

.nav button {
  flex: 1;
  background: var(--border);
  color: var(--text);
}

.submit {
  width: 100%;
  background: var(--correct);
}

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

.progress span {
  font-size: 0.85rem;
  color: var(--muted);
}

.progress-bar {
  height: 6px;
  background: var(--border);
  border-radius: 4px;
  margin-top: 4px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: var(--accent);
}

.prompt {
  font-size: 1.1rem;
  margin-bottom: 16px;
}

.options {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.option {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  cursor: pointer;
}

.fill-blank-prompt input.blank-answer {
  width: 140px;
  margin: 0 4px;
}

.answered-count {
  font-size: 0.85rem;
  color: var(--muted);
}

.error {
  color: var(--incorrect);
  margin-top: 8px;
}

.hint {
  font-size: 0.8rem;
  color: var(--muted);
  margin: 0;
}

.score {
  font-size: 2rem;
  font-weight: 700;
  margin: 8px 0;
}

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

.review-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-top: 16px;
}

.review-card {
  border: 1px solid var(--border);
  border-left-width: 4px;
  border-radius: 8px;
  padding: 14px;
}

.review-card.correct {
  border-left-color: var(--correct);
}

.review-card.incorrect {
  border-left-color: var(--incorrect);
}

.review-status {
  font-size: 0.85rem;
  color: var(--muted);
  margin: 0 0 8px;
}

.your-answer,
.correct-answer {
  margin: 4px 0;
}

.explanation {
  margin-top: 8px;
  padding-top: 8px;
  border-top: 1px dashed var(--border);
  color: var(--muted);
}