*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --bg: #0f1117;
  --surface: #1a1d27;
  --border: #2a2f3d;
  --text: #e8eaed;
  --muted: #9aa0a6;
  --accent: #6c8cff;
  --success: #34a853;
  --error: #ea4335;
  --card-bg: #ffffff;
  --radius: 16px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.5;
}

.app {
  max-width: 720px;
  margin: 0 auto;
  padding: 24px 16px 48px;
}

.header {
  text-align: center;
  margin-bottom: 28px;
}

.header h1 {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.subtitle {
  color: var(--muted);
  margin-top: 4px;
  font-size: 1rem;
}

.setup {
  margin-bottom: 32px;
}

.setup-title {
  text-align: center;
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: 16px;
}

.setup-options {
  display: grid;
  gap: 12px;
}

.setup-card {
  background: var(--surface);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  text-align: left;
  cursor: pointer;
  transition: border-color 0.15s ease, transform 0.15s ease, background 0.15s ease;
  color: var(--text);
}

.setup-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
  background: #1f2330;
}

.setup-card-title {
  display: block;
  font-size: 1.125rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.setup-card-desc {
  display: block;
  font-size: 0.875rem;
  color: var(--muted);
}

.game[hidden],
.setup[hidden] {
  display: none;
}

.stats {
  display: flex;
  justify-content: center;
  gap: 32px;
  margin-bottom: 24px;
}

.stat {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
}

.stat-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
}

.stat-value {
  font-size: 1.5rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

.difficulty {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  margin-bottom: 24px;
}

.difficulty-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
}

.difficulty-pills {
  display: flex;
  gap: 8px;
}

.pill {
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--muted);
  padding: 6px 16px;
  border-radius: 999px;
  font-size: 0.875rem;
  cursor: pointer;
  transition: all 0.15s ease;
}

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

.pill.active {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.pill:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.feedback {
  text-align: center;
  min-height: 2rem;
  margin-bottom: 16px;
  font-size: 1.05rem;
  font-weight: 500;
}

.feedback.success {
  color: var(--success);
}

.feedback.error {
  color: var(--error);
}

.choices {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-bottom: 24px;
}

.choice-card {
  position: relative;
  background: var(--card-bg);
  border: 3px solid var(--border);
  border-radius: var(--radius);
  padding: 24px 16px;
  cursor: pointer;
  transition: border-color 0.15s ease, transform 0.15s ease, box-shadow 0.15s ease;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  min-height: 200px;
}

.choice-card:hover:not(:disabled) {
  border-color: var(--accent);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.3);
}

.choice-card:disabled {
  cursor: default;
}

.choice-card.correct {
  border-color: var(--success);
  box-shadow: 0 0 0 2px var(--success);
}

.choice-card.incorrect {
  border-color: var(--error);
  opacity: 0.6;
}

.choice-card img {
  width: 100%;
  max-width: 140px;
  height: 120px;
  object-fit: contain;
}

.choice-label {
  font-size: 0.875rem;
  font-weight: 600;
  color: #555;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.actions {
  display: flex;
  justify-content: center;
}

.btn {
  padding: 12px 28px;
  border-radius: 999px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: opacity 0.15s ease;
}

.btn:hover {
  opacity: 0.9;
}

.btn-secondary {
  background: var(--surface);
  color: var(--text);
  border: 1px solid var(--border);
}

.loading {
  text-align: center;
  color: var(--muted);
  padding: 48px 0;
}

.loading[hidden],
.feedback:empty {
  display: none;
}

@media (max-width: 520px) {
  .choices {
    grid-template-columns: 1fr;
  }

  .stats {
    gap: 20px;
  }

  .stat-value {
    font-size: 1.25rem;
  }
}