:root {
  --color-primary: #0d9488;
  --color-primary-dark: #0f766e;
  --color-bg: #f4faf9;
  --color-surface: #ffffff;
  --color-text: #1f2937;
  --color-success: #16a34a;
  --color-error: #dc2626;
  --color-border: #d1e7e4;
}

* { box-sizing: border-box; }

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

.topnav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 24px;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 10;
}

.brand {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--color-primary-dark);
}

.topnav nav { display: flex; gap: 8px; }

.nav-btn {
  padding: 8px 16px;
  border: none;
  background: transparent;
  border-radius: 8px;
  cursor: pointer;
  font-size: 0.95rem;
  color: var(--color-text);
}

.nav-btn:hover { background: var(--color-bg); }
.nav-btn.active { background: var(--color-primary); color: white; }

main {
  max-width: 800px;
  margin: 0 auto;
  padding: 24px 16px;
}

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

.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 20px;
  margin-bottom: 16px;
}

.btn-primary {
  background: var(--color-primary);
  color: white;
  border: none;
  border-radius: 10px;
  padding: 14px 24px;
  font-size: 1.05rem;
  cursor: pointer;
}

.btn-primary:hover { background: var(--color-primary-dark); }
.btn-primary:disabled { background: #9ca3af; cursor: not-allowed; }

.btn-secondary {
  background: var(--color-surface);
  color: var(--color-primary-dark);
  border: 1px solid var(--color-primary);
  border-radius: 10px;
  padding: 10px 20px;
  cursor: pointer;
}

.error-banner {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: var(--color-error);
  color: white;
  text-align: center;
  padding: 10px;
  z-index: 100;
}

.error-banner.hidden { display: none; }

.mode-btn { margin: 4px 8px 4px 0; }
.mode-btn.active { background: var(--color-primary); color: white; }
#count-slider { accent-color: var(--color-primary); }

.result-summary { text-align: center; }

.result-percent {
  font-size: 3.5rem;
  font-weight: 800;
  color: var(--color-primary-dark);
}

.result-verdict {
  font-size: 1.4rem;
  margin: 8px 0;
}

.wrong-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 0;
  border-bottom: 1px solid var(--color-border);
}

.wrong-your { color: var(--color-error); }
.wrong-correct { color: var(--color-success); }

.speak-btn-small {
  background: none;
  border: none;
  cursor: pointer;
  font-size: 1.1rem;
}

.result-actions {
  display: flex;
  gap: 12px;
  margin-top: 16px;
}

.quiz-progress {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 24px;
}

.progress-bar {
  flex: 1;
  height: 8px;
  background: var(--color-border);
  border-radius: 4px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: var(--color-primary);
  transition: width 0.3s;
}

#streak-badge {
  color: var(--color-primary-dark);
  font-weight: 700;
  transition: transform 0.2s;
}

.streak-pop { transform: scale(1.4); }

.quiz-word-card {
  text-align: center;
  padding: 48px 0;
}

.quiz-word {
  font-size: 3rem;
  font-weight: 700;
  color: var(--color-text);
}

.speak-btn {
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  margin-left: 12px;
}

.options-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
}

.option-card {
  padding: 16px;
  border: 2px solid var(--color-border);
  border-radius: 10px;
  background: var(--color-surface);
  cursor: pointer;
  text-align: left;
  font-size: 1.05rem;
}

.option-card:hover { border-color: var(--color-primary); }

.option-num {
  display: inline-block;
  width: 24px;
  height: 24px;
  line-height: 24px;
  text-align: center;
  border-radius: 50%;
  background: var(--color-bg);
  margin-right: 10px;
  font-size: 0.85rem;
}

.option-card.correct {
  border-color: var(--color-success);
  background: #f0fdf4;
}

.option-card.incorrect {
  border-color: var(--color-error);
  background: #fef2f2;
}

.data-table {
  width: 100%;
  border-collapse: collapse;
}

.data-table th, .data-table td {
  text-align: left;
  padding: 10px;
  border-bottom: 1px solid var(--color-border);
}

.history-row { cursor: pointer; }
.history-row:hover { background: var(--color-bg); }

.detail-item {
  padding: 4px 0;
  font-size: 0.9rem;
}

.detail-item.wrong { color: var(--color-error); }

.btn-mastered {
  margin-left: auto;
  padding: 6px 12px;
  font-size: 0.85rem;
}

.chart-toggle {
  display: flex;
  gap: 8px;
  margin-bottom: 12px;
}

.toggle-btn.active {
  background: var(--color-primary);
  color: white;
}

canvas {
  max-width: 100%;
  height: auto;
}

.text-input {
  display: block;
  width: 100%;
  padding: 10px 12px;
  margin-bottom: 10px;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  font-size: 1rem;
  box-sizing: border-box;
}