/* ===== CSS Variables ===== */
:root {
  --primary-color: #3b82f6;
  --secondary-color: #8b5cf6;
  --accent-color: #06b6d4;
  --success-color: #10b981;
  --warning-color: #f59e0b;
  --danger-color: #ef4444;

  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-tertiary: #334155;
  --bg-card: #1e293b;

  --text-primary: #f1f5f9;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;

  --border-color: #475569;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5);

  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
}

/* ===== Reset & Base ===== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
}

.container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 20px;
}

/* ===== Header ===== */
.header {
  background: linear-gradient(135deg, #1a2744 0%, #0f172a 100%);
  padding: 2rem 0;
  border-bottom: 1px solid var(--border-color);
  box-shadow: var(--shadow-md);
}

.title {
  font-size: 2.5rem;
  font-weight: 700;
  background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 0.5rem;
}

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

/* ===== Two-Panel Layout ===== */
.two-panel-layout {
  display: grid;
  grid-template-columns: 300px 1fr;
  gap: 24px;
  padding: 24px 0;
}

/* ===== Control Panel ===== */
.control-panel {
  background: var(--bg-secondary);
  border-radius: var(--radius-lg);
  padding: 20px;
  border: 1px solid var(--border-color);
  height: fit-content;
  position: sticky;
  top: 20px;
  max-height: calc(100vh - 40px);
  overflow-y: auto;
}

.control-panel h2 {
  font-size: 1.3rem;
  margin-bottom: 16px;
  color: var(--primary-color);
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 8px;
}

.control-section {
  margin-bottom: 20px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--border-color);
}

.control-section:last-child {
  border-bottom: none;
  margin-bottom: 0;
}

.control-section h3 {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--accent-color);
  margin-bottom: 12px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.control-group {
  margin-bottom: 12px;
}

.control-group label {
  display: block;
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: 4px;
}

.control-select {
  width: 100%;
  padding: 8px 10px;
  background: var(--bg-tertiary);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  cursor: pointer;
  outline: none;
  transition: border-color 0.2s;
}

.control-select:focus {
  border-color: var(--primary-color);
}

.control-slider {
  width: 100%;
  height: 6px;
  -webkit-appearance: none;
  appearance: none;
  background: var(--bg-tertiary);
  border-radius: 3px;
  outline: none;
  cursor: pointer;
}

.control-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 16px;
  height: 16px;
  background: var(--primary-color);
  border-radius: 50%;
  cursor: pointer;
  transition: transform 0.15s;
}

.control-slider::-webkit-slider-thumb:hover {
  transform: scale(1.2);
}

.control-slider::-moz-range-thumb {
  width: 16px;
  height: 16px;
  background: var(--primary-color);
  border-radius: 50%;
  cursor: pointer;
  border: none;
}

/* ===== File Input ===== */
.file-input {
  display: none;
}

.file-label {
  display: inline-block;
  padding: 8px 16px;
  background: var(--bg-tertiary);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  cursor: pointer;
  transition: all 0.2s;
  margin-bottom: 4px;
}

.file-label:hover {
  background: var(--primary-color);
  border-color: var(--primary-color);
}

.file-name {
  display: block;
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 4px;
  word-break: break-all;
}

/* ===== Buttons ===== */
.btn-primary {
  padding: 10px 20px;
  background: var(--primary-color);
  color: white;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  width: 100%;
}

.btn-primary:hover {
  background: #2563eb;
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-primary:active {
  transform: translateY(0);
}

.btn-secondary {
  padding: 10px 20px;
  background: var(--bg-tertiary);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  cursor: pointer;
  transition: all 0.2s;
  width: 100%;
}

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

.btn-group {
  display: flex;
  gap: 8px;
}

.btn-group .btn-primary,
.btn-group .btn-secondary {
  flex: 1;
}

/* ===== Visualization Panel ===== */
.visualization-panel {
  min-width: 0;
}

.chart-container {
  background: var(--bg-secondary);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-color);
  padding: 16px;
  margin-bottom: 16px;
  box-shadow: var(--shadow-sm);
}

.chart-large {
  padding: 16px;
}

.chart-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 12px;
  flex-wrap: wrap;
  gap: 8px;
}

.chart-header h3 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
}

.chart-info {
  font-size: 0.8rem;
  color: var(--text-muted);
  background: var(--bg-tertiary);
  padding: 2px 8px;
  border-radius: var(--radius-sm);
}

.chart-controls {
  display: flex;
  gap: 8px;
  align-items: center;
  flex-wrap: wrap;
}

/* ===== Canvas Wrappers ===== */
.canvas-wrapper {
  position: relative;
  width: 100%;
  background: #0a0a0a;
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.canvas-wrapper canvas {
  display: block;
  width: 100%;
  height: 150px;
}

.spectrogram-wrapper {
  position: relative;
  width: 100%;
  background: #0a0a0a;
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.spectrogram-wrapper canvas {
  display: block;
  width: 100%;
  height: 400px;
}

.spectrogram-wrapper #cursor-canvas {
  position: absolute;
  top: 0;
  left: 0;
  pointer-events: none;
}

.spectrogram-axis-labels {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 24px;
  margin-top: 8px;
}

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

.axis-label.y-axis {
  writing-mode: vertical-lr;
  text-orientation: mixed;
  transform: rotate(180deg);
}

/* ===== Legend ===== */
.legend-wrapper {
  display: flex;
  align-items: stretch;
  gap: 8px;
  height: 50px;
}

.legend-wrapper canvas {
  width: 100%;
  height: 100%;
  border-radius: var(--radius-sm);
}

.legend-labels {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  font-size: 0.75rem;
  color: var(--text-muted);
  white-space: nowrap;
}

/* ===== Stats Grid ===== */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin-bottom: 16px;
}

.stat-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 12px 16px;
  text-align: center;
  transition: border-color 0.2s;
}

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

.stat-label {
  display: block;
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-bottom: 4px;
  text-transform: uppercase;
  letter-spacing: 0.3px;
}

.stat-value {
  display: block;
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--accent-color);
  font-variant-numeric: tabular-nums;
}

/* ===== Education Section ===== */
.education-section {
  margin-top: 40px;
  padding-top: 32px;
  border-top: 2px solid var(--border-color);
}

.education-section > h2 {
  font-size: 1.8rem;
  font-weight: 700;
  margin-bottom: 24px;
  background: linear-gradient(135deg, var(--secondary-color), var(--accent-color));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.education-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}

.edu-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 24px;
  transition: transform 0.2s, border-color 0.2s;
}

.edu-card:hover {
  transform: translateY(-2px);
  border-color: var(--primary-color);
}

.edu-card h3 {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--primary-color);
  margin-bottom: 12px;
}

.edu-card p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  line-height: 1.7;
}

.app-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.app-item {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.app-item strong {
  color: var(--accent-color);
}

.formula-block {
  background: var(--bg-tertiary);
  padding: 16px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
}

.formula {
  font-family: 'Courier New', Courier, monospace;
  font-size: 0.95rem;
  color: var(--accent-color);
  margin-bottom: 8px;
  word-break: break-word;
}

.formula-desc {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.howto-list {
  list-style: none;
  counter-reset: step-counter;
}

.howto-list li {
  counter-increment: step-counter;
  position: relative;
  padding-left: 32px;
  margin-bottom: 10px;
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.howto-list li::before {
  content: counter(step-counter);
  position: absolute;
  left: 0;
  top: 2px;
  width: 24px;
  height: 24px;
  background: var(--primary-color);
  color: white;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  font-weight: 700;
}

/* ===== Footer ===== */
.footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 2rem 0;
  text-align: center;
  margin-top: 40px;
}

.footer p {
  color: var(--text-muted);
  font-style: italic;
  font-size: 0.95rem;
}

/* ===== Scrollbar ===== */
.control-panel::-webkit-scrollbar {
  width: 6px;
}

.control-panel::-webkit-scrollbar-track {
  background: var(--bg-primary);
}

.control-panel::-webkit-scrollbar-thumb {
  background: var(--border-color);
  border-radius: 3px;
}

.control-panel::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}

/* ===== Responsive ===== */
@media (max-width: 1024px) {
  .two-panel-layout {
    grid-template-columns: 1fr;
  }

  .control-panel {
    position: static;
    max-height: none;
  }

  .education-grid {
    grid-template-columns: 1fr;
  }

  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 640px) {
  .header {
    padding: 1.5rem 0;
  }

  .title {
    font-size: 1.6rem;
  }

  .subtitle {
    font-size: 0.95rem;
  }

  .stats-grid {
    grid-template-columns: 1fr;
  }

  .spectrogram-wrapper canvas {
    height: 280px;
  }

  .edu-card {
    padding: 16px;
  }

  .btn-group {
    flex-direction: column;
  }
}