:root {
  --color-bg: #0f172a;
  --color-surface: #1e293b;
  --color-surface-2: #273549;
  --color-border: #334155;
  --color-text: #e2e8f0;
  --color-text-dim: #94a3b8;
  --color-primary: #2563eb;
  --color-primary-hover: #1d4ed8;
  --color-correct: #16a34a;
  --color-correct-bg: #14532d;
  --color-wrong: #dc2626;
  --color-wrong-bg: #7f1d1d;
  --radius: 10px;
}

* { box-sizing: border-box; }

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

.app-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  padding: 10px 16px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 10px;
}

.app-header h1 {
  font-size: 1.15rem;
  margin: 0;
  white-space: nowrap;
}

.cat-tabs {
  display: flex;
  gap: 6px;
}

.cat-tab {
  background: var(--color-surface-2);
  color: var(--color-text);
  border: 1px solid var(--color-border);
  padding: 10px 18px;
  border-radius: var(--radius);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  min-width: 48px;
}

.cat-tab.active {
  background: var(--color-primary);
  border-color: var(--color-primary);
}

main#app {
  max-width: 760px;
  margin: 0 auto;
  padding: 16px 12px 60px;
}

.mode-bar {
  margin-bottom: 16px;
}

.segmented {
  display: flex;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  overflow: hidden;
}

.segmented.small {
  font-size: 0.85rem;
}

.seg-btn {
  flex: 1;
  background: transparent;
  color: var(--color-text-dim);
  border: none;
  padding: 12px 10px;
  cursor: pointer;
  font-size: 0.95rem;
  font-weight: 500;
  border-right: 1px solid var(--color-border);
}

.seg-btn:last-child { border-right: none; }

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

.view { display: none; }
.view.active { display: block; }

/* ---- List mode ---- */
.q-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 16px;
  margin-bottom: 14px;
}

.q-index {
  color: var(--color-text-dim);
  font-size: 0.8rem;
  margin-bottom: 4px;
}

.q-text {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 10px;
}

.q-image {
  max-width: 100%;
  max-height: 260px;
  display: block;
  margin: 0 auto 12px;
  background: #fff;
  border-radius: 6px;
  padding: 6px;
}

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

/* ---- Bookmark / mistake-tracking extras ---- */
.q-extras {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin-top: 14px;
  margin-bottom: 8px;
}

.tag-btn {
  background: var(--color-surface-2);
  color: var(--color-text-dim);
  border: 1px solid var(--color-border);
  border-radius: 999px;
  padding: 6px 12px;
  font-size: 0.8rem;
  cursor: pointer;
}

.tag-btn.active[data-bm="mistake"] {
  background: #7c2d12;
  border-color: #f97316;
  color: #fed7aa;
}

.tag-btn.active[data-bm="study"] {
  background: #1e3a5f;
  border-color: #3b82f6;
  color: #bfdbfe;
}

.note-textarea {
  display: block;
  width: 100%;
  min-height: 56px;
  margin-bottom: 12px;
  padding: 8px 10px;
  border-radius: 8px;
  border: 1px solid var(--color-border);
  background: var(--color-surface-2);
  color: var(--color-text);
  font-family: inherit;
  font-size: 0.9rem;
  resize: vertical;
}

.note-textarea:focus {
  outline: none;
  border-color: var(--color-primary);
}

.note-textarea::placeholder {
  color: var(--color-text-dim);
}

.stat-badge {
  font-size: 0.8rem;
  color: var(--color-text-dim);
  background: var(--color-surface-2);
  border: 1px solid var(--color-border);
  border-radius: 999px;
  padding: 6px 12px;
}

/* ---- Mistakes chart (Historie) ---- */
.mistakes-chart {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 16px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 12px;
}

.chart-bar-row {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 0.8rem;
}

.chart-bar-label {
  width: 64px;
  flex-shrink: 0;
  color: var(--color-text-dim);
  font-weight: 600;
}

.chart-bar-track {
  flex: 1;
  display: flex;
  height: 14px;
  background: var(--color-surface-2);
  border-radius: 4px;
  overflow: hidden;
}

.chart-bar-seg.correct {
  background: var(--color-correct);
  height: 100%;
}

.chart-bar-seg.wrong {
  background: var(--color-wrong);
  height: 100%;
}

.chart-bar-count {
  width: 92px;
  flex-shrink: 0;
  text-align: right;
  color: var(--color-text-dim);
}

/* ---- Mistakes list (Historie) ---- */
.mistakes-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.mistake-row {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 12px 14px;
}

.mistake-text {
  font-size: 0.95rem;
  margin-bottom: 6px;
}

.mistake-meta {
  font-size: 0.85rem;
  color: var(--color-text-dim);
  margin-bottom: 8px;
}

.opt-row {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border-radius: 8px;
  border: 1px solid var(--color-border);
  background: var(--color-surface-2);
}

.opt-row.is-correct {
  border-color: var(--color-correct);
  background: var(--color-correct-bg);
}

.opt-key {
  font-weight: 700;
  min-width: 22px;
}

.opt-img {
  max-width: 90px;
  max-height: 70px;
  background: #fff;
  border-radius: 4px;
  padding: 3px;
}

/* ---- Test mode ---- */
.test-controls {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 14px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 12px;
}

.toggle-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.toggle-label {
  font-size: 0.8rem;
  color: var(--color-text-dim);
}

.test-status {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 10px;
  font-size: 0.95rem;
  color: var(--color-text-dim);
}

.score-label {
  font-weight: 600;
  color: var(--color-text);
}

.question-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 18px;
  min-height: 200px;
}

.opt-btn {
  display: flex;
  align-items: center;
  gap: 12px;
  width: 100%;
  text-align: left;
  padding: 14px 14px;
  margin-bottom: 10px;
  border-radius: 10px;
  border: 1px solid var(--color-border);
  background: var(--color-surface-2);
  color: var(--color-text);
  font-size: 1rem;
  cursor: pointer;
}

.opt-btn:active { transform: scale(0.995); }

.opt-btn.correct {
  border-color: var(--color-correct);
  background: var(--color-correct-bg);
}

.opt-btn.wrong {
  border-color: var(--color-wrong);
  background: var(--color-wrong-bg);
}

.opt-btn:disabled {
  cursor: default;
  opacity: 0.95;
}

.test-nav {
  display: flex;
  gap: 8px;
  margin-top: 14px;
  flex-wrap: wrap;
}

.btn {
  flex: 1;
  padding: 13px 14px;
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
  background: var(--color-surface-2);
  color: var(--color-text);
  font-size: 0.95rem;
  cursor: pointer;
  min-width: 100px;
}

.btn.small { flex: none; padding: 8px 12px; font-size: 0.85rem; }

.btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

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

.btn-secondary {
  background: var(--color-surface);
}

.btn-danger {
  background: var(--color-wrong-bg);
  border-color: var(--color-wrong);
}

/* ---- Summary ---- */
.summary-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 24px;
  text-align: center;
}

.summary-card .big-score {
  font-size: 2.4rem;
  font-weight: 700;
  margin: 8px 0;
}

.summary-card .percent {
  font-size: 1.3rem;
  color: var(--color-text-dim);
  margin-bottom: 14px;
}

.summary-meta {
  color: var(--color-text-dim);
  font-size: 0.9rem;
}

.summary-actions {
  display: flex;
  gap: 10px;
  margin-top: 16px;
}

/* ---- History ---- */
.history-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 12px;
}

.history-header h2 {
  font-size: 1.05rem;
  margin: 0;
}

.backup-actions {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 10px;
}

.backup-hint {
  margin: -2px 0 22px;
}

.history-chart {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 10px;
  margin-bottom: 14px;
}

.history-list table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}

.history-list th, .history-list td {
  text-align: left;
  padding: 8px 6px;
  border-bottom: 1px solid var(--color-border);
}

.history-empty {
  color: var(--color-text-dim);
  padding: 20px 0;
  text-align: center;
}

.loading {
  text-align: center;
  padding: 40px 0;
  color: var(--color-text-dim);
  display: none;
}

.loading.active { display: block; }

@media (min-width: 600px) {
  .test-controls {
    flex-direction: row;
    flex-wrap: wrap;
    align-items: flex-end;
    justify-content: space-between;
  }
  .toggle-group { flex: 1 1 160px; }
  #restartBtn { flex: none; }
}