:root {
  color-scheme: light dark;
  --bg: #0f1117;
  --panel: #171a24;
  --panel-border: #2a2e3d;
  --text: #e8eaf2;
  --muted: #9199b0;
  --accent: #6c8cff;
  --accent-2: #37d67a;
  --danger: #ff5c72;
  --easy: #37d67a;
  --medium: #ffb454;
  --hard: #ff5c72;
}

* { box-sizing: border-box; }

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

.app {
  max-width: 860px;
  margin: 0 auto;
  padding: 32px 20px 80px;
}

.app-header h1 {
  margin: 0 0 6px;
  font-size: 1.7rem;
}

.subtitle {
  color: var(--muted);
  margin: 0 0 28px;
}

.screen.hidden { display: none; }

.setup-toolbar {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.question-count-control {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--muted);
}

.question-count-control input {
  width: 64px;
  padding: 6px 8px;
  border-radius: 8px;
  border: 1px solid var(--panel-border);
  background: var(--panel);
  color: var(--text);
  font-size: 0.95rem;
}

.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 14px;
  margin-bottom: 24px;
}

.topic-card {
  background: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: 12px;
  padding: 14px 16px;
  cursor: pointer;
  transition: border-color 0.15s ease, background 0.15s ease;
  user-select: none;
}

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

.topic-card.selected {
  border-color: var(--accent);
  background: #1b2140;
}

.topic-card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-weight: 600;
}

.topic-card-count {
  color: var(--muted);
  font-weight: 400;
  font-size: 0.85rem;
}

.setup-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
  border-top: 1px solid var(--panel-border);
  padding-top: 20px;
}

.selected-summary {
  color: var(--muted);
  font-size: 0.9rem;
}

.btn {
  border: none;
  border-radius: 10px;
  padding: 10px 18px;
  font-size: 0.95rem;
  cursor: pointer;
  font-weight: 600;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
}

.btn-primary:disabled {
  background: #333850;
  color: var(--muted);
  cursor: not-allowed;
}

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

.btn-danger {
  background: var(--danger);
  color: #fff;
}

.test-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 24px;
  position: sticky;
  top: 0;
  background: var(--bg);
  padding: 12px 0;
  z-index: 5;
}

.timer {
  font-size: 2rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  letter-spacing: 1px;
}

.timer.warning { color: var(--medium); }
.timer.critical { color: var(--danger); }

.question-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.question-card {
  background: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: 12px;
  padding: 18px 20px;
}

.question-card-top {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 6px;
}

.question-name {
  font-size: 1.1rem;
  font-weight: 600;
}

.question-meta {
  color: var(--muted);
  font-size: 0.85rem;
  margin-bottom: 10px;
}

.difficulty {
  font-weight: 600;
}

.difficulty.Easy { color: var(--easy); }
.difficulty.Medium { color: var(--medium); }
.difficulty.Hard { color: var(--hard); }

.question-link {
  color: var(--accent);
  text-decoration: none;
  font-size: 0.95rem;
}

.question-link:hover {
  text-decoration: underline;
}

.results-summary {
  color: var(--muted);
  margin-bottom: 20px;
}

#new-test-btn {
  margin-top: 24px;
}