:root {
  --bg: #fbf9f4;
  --fg: #232020;
  --muted: #6b6560;
  --card: #ffffff;
  --border: #e6e0d6;
  --accent: #3b5bdb;
  --correct: #2f9e44;
  --wrong: #e03131;
  color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1a1817;
    --fg: #ececec;
    --muted: #a29b93;
    --card: #262322;
    --border: #3a3634;
    --accent: #91a7ff;
    --correct: #69db7c;
    --wrong: #ff8787;
  }
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: ui-serif, Georgia, "Times New Roman", serif;
  background: var(--bg);
  color: var(--fg);
  line-height: 1.5;
}

#app {
  max-width: 40rem;
  margin: 0 auto;
  padding: 2rem 1.25rem 4rem;
}

header {
  margin-bottom: 1.5rem;
}

h1 {
  font-size: 1.9rem;
  margin: 0.25rem 0 0;
}

.tagline {
  color: var(--muted);
  margin: 0.25rem 0 0;
}

.back {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.9rem;
}

.back:hover {
  color: var(--accent);
}

/* Home: set list */
.set-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 0.75rem;
}

.set-card {
  display: grid;
  gap: 0.2rem;
  padding: 1rem 1.15rem;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 0.75rem;
  text-decoration: none;
  color: inherit;
  transition: border-color 0.15s ease;
}

.set-card:hover {
  border-color: var(--accent);
}

.set-title {
  font-size: 1.2rem;
  font-weight: 600;
}

.set-desc {
  color: var(--muted);
}

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

/* Play */
.progress {
  color: var(--muted);
  font-size: 0.9rem;
  margin: 0;
}

.prompt {
  font-size: 1.35rem;
  margin: 0.5rem 0 1.25rem;
}

.choices {
  display: grid;
  gap: 0.6rem;
}

button {
  font: inherit;
  cursor: pointer;
}

.choice {
  text-align: left;
  padding: 0.8rem 1rem;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 0.6rem;
  color: inherit;
  transition: border-color 0.15s ease;
}

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

.choice:disabled {
  cursor: default;
  opacity: 0.9;
}

.choice.correct {
  border-color: var(--correct);
  color: var(--correct);
  font-weight: 600;
}

.choice.wrong {
  border-color: var(--wrong);
  color: var(--wrong);
}

.explanation {
  margin: 1.25rem 0 0;
  padding: 0.9rem 1.1rem;
  background: var(--card);
  border-left: 3px solid var(--accent);
  border-radius: 0 0.5rem 0.5rem 0;
  color: var(--fg);
}

.next {
  margin-top: 1.25rem;
  padding: 0.7rem 1.4rem;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 0.6rem;
  font-weight: 600;
}

/* Results */
.score {
  font-size: 1.4rem;
  font-weight: 600;
}

.review {
  list-style: none;
  padding: 0;
  margin: 1rem 0 1.5rem;
  display: grid;
  gap: 0.75rem;
}

.review li {
  display: grid;
  gap: 0.25rem;
  padding: 0.9rem 1.1rem;
  background: var(--card);
  border: 1px solid var(--border);
  border-left-width: 3px;
  border-radius: 0 0.5rem 0.5rem 0;
}

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

.review li.wrong {
  border-left-color: var(--wrong);
}

.review-prompt {
  font-weight: 600;
}

.review-answer {
  color: var(--muted);
  font-size: 0.95rem;
}

.review-explanation {
  color: var(--muted);
  font-size: 0.95rem;
}