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

:root {
  --color-bg: #f0f2f5;
  --color-surface: #ffffff;
  --color-primary: #4a6cf7;
  --color-primary-hover: #3b5de7;
  --color-correct: #22c55e;
  --color-correct-bg: #dcfce7;
  --color-wrong: #ef4444;
  --color-wrong-bg: #fef2f2;
  --color-text: #1e293b;
  --color-text-secondary: #64748b;
  --color-border: #e2e8f0;
  --radius: 12px;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.08), 0 1px 2px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 4px 12px rgba(0, 0, 0, 0.1);
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  min-height: 100vh;
}

#app {
  max-width: 640px;
  margin: 0 auto;
  padding: 16px;
}

/* Header */
.header {
  text-align: center;
  margin-bottom: 20px;
}

.header h1 {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 16px;
  color: var(--color-text);
}

/* Navigation Tabs */
.nav-tabs {
  display: flex;
  background: var(--color-surface);
  border-radius: var(--radius);
  padding: 4px;
  box-shadow: var(--shadow);
}

.nav-tab {
  flex: 1;
  padding: 10px 16px;
  border: none;
  background: transparent;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--color-text-secondary);
  cursor: pointer;
  border-radius: 8px;
  transition: all 0.2s;
}

.nav-tab.active {
  background: var(--color-primary);
  color: white;
}

.nav-tab:hover:not(.active) {
  color: var(--color-text);
  background: var(--color-bg);
}

/* Tab Content */
.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
}

/* Cards */
.card {
  background: var(--color-surface);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 16px;
  box-shadow: var(--shadow);
}

.card h2 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 16px;
  color: var(--color-text);
}

.card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 12px;
  color: var(--color-text);
}

/* Range Configuration */
.range-inputs {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 12px;
}

.input-group {
  flex: 1;
}

.input-group label {
  display: block;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-text-secondary);
  margin-bottom: 4px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.input-group input,
.auto-play-config input {
  width: 100%;
  padding: 10px 12px;
  border: 2px solid var(--color-border);
  border-radius: 8px;
  font-size: 1rem;
  transition: border-color 0.2s;
  outline: none;
}

.input-group input:focus,
.auto-play-config input:focus {
  border-color: var(--color-primary);
}

.range-separator {
  color: var(--color-text-secondary);
  font-size: 1.2rem;
  padding-top: 20px;
}

.preset-buttons {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}

.preset-btn {
  padding: 8px 16px;
  border: 2px solid var(--color-border);
  border-radius: 8px;
  background: var(--color-surface);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: all 0.2s;
}

.preset-btn:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

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

.auto-play-config {
  display: flex;
  align-items: center;
  gap: 12px;
}

.auto-play-config label {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  white-space: nowrap;
}

.auto-play-config input {
  width: 80px;
}

/* Play Section */
.play-section {
  text-align: center;
}

.play-controls {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 12px;
  margin-bottom: 20px;
}

.play-btn {
  width: 72px;
  height: 72px;
  border-radius: 50%;
  border: none;
  background: var(--color-primary);
  color: white;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s;
  box-shadow: var(--shadow-lg);
}

.play-btn:hover {
  background: var(--color-primary-hover);
  transform: scale(1.05);
}

.play-btn:active {
  transform: scale(0.98);
}

.play-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
}

.stop-btn {
  width: 72px;
  height: 72px;
  border-radius: 50%;
  border: none;
  background: var(--color-wrong);
  color: white;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s;
  box-shadow: var(--shadow-lg);
}

.stop-btn:hover {
  background: #dc2626;
  transform: scale(1.05);
}

.stop-btn:active {
  transform: scale(0.98);
}

.replay-btn {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 2px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s;
}

.replay-btn:hover:not(:disabled) {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.replay-btn:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}

/* Answer Area */
.answer-area {
  max-width: 320px;
  margin: 0 auto;
}

.answer-input {
  width: 100%;
  padding: 14px 16px;
  border: 2px solid var(--color-border);
  border-radius: var(--radius);
  font-size: 1.5rem;
  text-align: center;
  outline: none;
  transition: border-color 0.2s;
  letter-spacing: 1px;
}

.answer-input:focus {
  border-color: var(--color-primary);
}

.answer-input:disabled {
  background: var(--color-bg);
  color: var(--color-text-secondary);
}

.answer-input.correct {
  border-color: var(--color-correct);
  background: var(--color-correct-bg);
}

.answer-input.wrong {
  border-color: var(--color-wrong);
  background: var(--color-wrong-bg);
}

/* Feedback */
.feedback {
  margin-top: 12px;
  padding: 10px 16px;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 600;
  transition: all 0.3s;
}

.feedback.correct {
  background: var(--color-correct-bg);
  color: var(--color-correct);
}

.feedback.wrong {
  background: var(--color-wrong-bg);
  color: var(--color-wrong);
}

.feedback.hidden {
  display: none;
}

.reaction-time {
  margin-top: 8px;
  font-size: 0.85rem;
  color: var(--color-text-secondary);
}

.reaction-time.hidden {
  display: none;
}

/* Stats Grid */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
}

.stat-item {
  text-align: center;
  padding: 8px;
}

.stat-value {
  display: block;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-text);
}

.stat-value.correct {
  color: var(--color-correct);
}

.stat-value.wrong {
  color: var(--color-wrong);
}

.stat-label {
  display: block;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--color-text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-top: 2px;
}

/* Analytics */
.analytics-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.analytics-header h2 {
  margin-bottom: 0;
}

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

.analytics-content.hidden {
  display: none;
}

.clear-history-btn {
  padding: 6px 14px;
  border: 2px solid var(--color-wrong);
  border-radius: 8px;
  background: transparent;
  color: var(--color-wrong);
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
}

.clear-history-btn:hover {
  background: var(--color-wrong);
  color: white;
}

/* Pattern List */
.pattern-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.pattern-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 14px;
  background: var(--color-bg);
  border-radius: 8px;
}

.pattern-item .number {
  font-weight: 700;
  font-size: 1.1rem;
}

.pattern-item .detail {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
}

.pattern-item .detail .wrong-answer {
  color: var(--color-wrong);
  font-weight: 600;
}

.pattern-item .bar-container {
  flex: 1;
  margin: 0 12px;
  height: 6px;
  background: var(--color-border);
  border-radius: 3px;
  overflow: hidden;
}

.pattern-item .bar {
  height: 100%;
  border-radius: 3px;
  transition: width 0.3s;
}

.pattern-item .bar.error-bar {
  background: var(--color-wrong);
}

.pattern-item .bar.slow-bar {
  background: #f59e0b;
}

.pattern-empty {
  color: var(--color-text-secondary);
  text-align: center;
  padding: 12px;
  font-size: 0.9rem;
}

.analytics-desc {
  font-size: 0.82rem;
  color: var(--color-text-secondary);
  margin-bottom: 12px;
}

/* Number Pad */
.numpad {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
  max-width: 320px;
  margin: 16px auto 0;
}

.numpad-btn {
  padding: 16px 0;
  border: 2px solid var(--color-border);
  border-radius: 10px;
  background: var(--color-surface);
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--color-text);
  cursor: pointer;
  transition: all 0.15s;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}

.numpad-btn:active {
  background: var(--color-bg);
  transform: scale(0.96);
}

.numpad-btn.numpad-fn {
  font-size: 1.1rem;
  color: var(--color-text-secondary);
}

.numpad-btn.numpad-submit {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: white;
  font-weight: 700;
}

.numpad-btn.numpad-submit:active {
  background: var(--color-primary-hover);
}

@media (hover: hover) {
  .numpad-btn:hover {
    border-color: var(--color-primary);
    color: var(--color-primary);
  }
  .numpad-btn.numpad-submit:hover {
    background: var(--color-primary-hover);
    color: white;
  }
}

/* Responsive */
@media (max-width: 480px) {
  #app {
    padding: 12px;
  }

  .header h1 {
    font-size: 1.2rem;
  }

  .stats-grid {
    grid-template-columns: repeat(3, 1fr);
    gap: 8px;
  }

  .stat-value {
    font-size: 1.2rem;
  }

  .preset-buttons {
    justify-content: center;
  }

  .answer-input {
    font-size: 1.3rem;
  }

  .play-btn {
    width: 64px;
    height: 64px;
  }

  .auto-play-config {
    flex-direction: column;
    align-items: flex-start;
  }

  .auto-play-config input {
    width: 100%;
  }
}