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

    :root {
      --bg-primary: #0a0a0f;
      --bg-secondary: #13131a;
      --bg-tertiary: #1a1a24;
      --accent-primary: #8b5cf6;
      --accent-secondary: #a78bfa;
      --accent-pink: #ec4899;
      --accent-cyan: #06b6d4;
      --accent-glow: rgba(139, 92, 246, 0.3);
      --accent-pink-glow: rgba(236, 72, 153, 0.3);
      --accent-cyan-glow: rgba(6, 182, 212, 0.3);
      --text-primary: #f8fafc;
      --text-secondary: #94a3b8;
      --text-muted: #64748b;
      --border-color: #2d2d3a;
      --success: #10b981;
      --warning: #8b5cf6;
    }

    body {
      font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
      background: var(--bg-primary);
      color: var(--text-primary);
      min-height: 100vh;
      display: flex;
      flex-direction: column;
      overflow-x: hidden;
    }

    header {
      background: var(--bg-secondary);
      border-bottom: 1px solid var(--border-color);
      padding: 1rem 2rem;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }

    .logo {
      display: flex;
      align-items: center;
      gap: 0.75rem;
    }

    .logo-icon {
      width: 40px;
      height: 40px;
      background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
      border-radius: 10px;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 1.5rem;
    }

    .logo-text h1 {
      font-size: 1.25rem;
      font-weight: 600;
      background: linear-gradient(135deg, var(--text-primary), var(--accent-secondary));
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      background-clip: text;
    }

    .logo-text span {
      font-size: 0.75rem;
      color: var(--text-muted);
    }

    .header-controls {
      display: flex;
      gap: 1rem;
      align-items: center;
    }

    main {
      flex: 1;
      display: flex;
      flex-direction: column;
      padding: 2rem;
      gap: 2rem;
      max-width: 1400px;
      margin: 0 auto;
      width: 100%;
    }

    .start-overlay {
      position: fixed;
      inset: 0;
      background: rgba(10, 10, 15, 0.95);
      display: flex;
      align-items: center;
      justify-content: center;
      z-index: 1000;
      backdrop-filter: blur(10px);
    }

    .start-overlay.hidden {
      display: none;
    }

    .start-content {
      text-align: center;
      max-width: 500px;
      padding: 2rem;
    }

    .start-content h2 {
      font-size: 2rem;
      margin-bottom: 1rem;
      background: linear-gradient(135deg, var(--text-primary), var(--accent-secondary));
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      background-clip: text;
    }

    .start-content p {
      color: var(--text-secondary);
      margin-bottom: 2rem;
      line-height: 1.6;
    }

    .start-btn {
      background: linear-gradient(135deg, var(--accent-primary), var(--accent-pink));
      color: white;
      border: none;
      padding: 1rem 3rem;
      font-size: 1.25rem;
      font-weight: 600;
      border-radius: 12px;
      cursor: pointer;
      transition: all 0.3s ease;
      box-shadow: 0 4px 20px var(--accent-glow);
    }

    .start-btn:hover {
      transform: translateY(-2px);
      box-shadow: 0 8px 30px var(--accent-pink-glow);
    }

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

    .loading-status {
      margin-top: 1rem;
      color: var(--accent-secondary);
      font-size: 0.875rem;
    }

    .chord-display {
      background: var(--bg-secondary);
      border: 1px solid var(--border-color);
      border-radius: 16px;
      padding: 2rem;
      text-align: center;
    }

    .chord-display h3 {
      font-size: 0.875rem;
      color: var(--text-muted);
      text-transform: uppercase;
      letter-spacing: 0.1em;
      margin-bottom: 1rem;
    }

    .current-note {
      font-size: 4rem;
      font-weight: 700;
      background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      background-clip: text;
      min-height: 5rem;
      display: flex;
      align-items: center;
      justify-content: center;
      transition: all 0.15s ease;
    }

    .current-note.playing {
      transform: scale(1.05);
      text-shadow: 0 0 40px var(--accent-glow);
    }

    .note-info {
      font-size: 1rem;
      color: var(--text-secondary);
      margin-top: 0.5rem;
    }

    .waveform-display {
      height: 80px;
      background: var(--bg-tertiary);
      border-radius: 8px;
      margin-top: 1rem;
      position: relative;
      overflow: hidden;
    }

    .waveform-bar {
      position: absolute;
      bottom: 0;
      width: 3px;
      background: var(--accent-pink);
      transition: height 0.05s ease;
    }

    .controls-section {
      background: var(--bg-secondary);
      border: 1px solid var(--border-color);
      border-radius: 16px;
      padding: 1.5rem;
    }

    .controls-section h3 {
      font-size: 0.875rem;
      color: var(--text-muted);
      text-transform: uppercase;
      letter-spacing: 0.1em;
      margin-bottom: 1.5rem;
      text-align: center;
    }

    .controls-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
      gap: 1.5rem;
    }

    .control-item {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 0.75rem;
    }

    .control-label {
      font-size: 0.75rem;
      color: var(--text-secondary);
      text-transform: uppercase;
      letter-spacing: 0.05em;
    }

    .control-value {
      font-size: 1.25rem;
      font-weight: 600;
      color: var(--accent-pink);
    }

    .control-slider {
      width: 100%;
      max-width: 120px;
      height: 6px;
      background: var(--bg-tertiary);
      border-radius: 3px;
      -webkit-appearance: none;
      cursor: pointer;
    }

    .control-slider::-webkit-slider-thumb {
      -webkit-appearance: none;
      width: 18px;
      height: 18px;
      background: var(--accent-pink);
      border-radius: 50%;
      cursor: pointer;
      transition: all 0.2s ease;
    }

    .control-slider::-webkit-slider-thumb:hover {
      transform: scale(1.1);
      box-shadow: 0 0 10px var(--accent-pink-glow);
    }

    .keyboard-section {
      background: var(--bg-secondary);
      border: 1px solid var(--border-color);
      border-radius: 16px;
      padding: 2rem;
    }

    .keyboard-section h3 {
      font-size: 0.875rem;
      color: var(--text-muted);
      text-transform: uppercase;
      letter-spacing: 0.1em;
      margin-bottom: 1.5rem;
      text-align: center;
    }

    .keyboard-row {
      display: flex;
      justify-content: center;
      gap: 0.5rem;
      flex-wrap: wrap;
    }

    .key {
      width: 70px;
      height: 90px;
      background: var(--bg-tertiary);
      border: 2px solid var(--border-color);
      border-radius: 8px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      cursor: pointer;
      transition: all 0.15s ease;
      user-select: none;
    }

    .key:hover {
      border-color: var(--accent-primary);
      background: rgba(139, 92, 246, 0.1);
    }

    .key.active {
      background: var(--accent-primary);
      border-color: var(--accent-primary);
      transform: scale(0.95);
      box-shadow: 0 0 20px var(--accent-glow);
    }

    .key-letter {
      font-size: 1.5rem;
      font-weight: 600;
      color: var(--text-primary);
    }

    .key-note {
      font-size: 0.75rem;
      color: var(--text-muted);
      margin-top: 0.25rem;
    }

    .key.active .key-letter,
    .key.active .key-note {
      color: white;
    }

    .sample-info {
      background: var(--bg-secondary);
      border: 1px solid var(--border-color);
      border-radius: 16px;
      padding: 1.5rem;
    }

    .sample-info h3 {
      font-size: 0.875rem;
      color: var(--text-muted);
      text-transform: uppercase;
      letter-spacing: 0.1em;
      margin-bottom: 1rem;
    }

    .sample-list {
      display: flex;
      flex-wrap: wrap;
      gap: 0.5rem;
    }

    .sample-tag {
      background: var(--bg-tertiary);
      padding: 0.5rem 1rem;
      border-radius: 6px;
      font-size: 0.75rem;
      color: var(--text-secondary);
    }

    .sample-tag.loaded {
      background: rgba(34, 197, 94, 0.2);
      color: var(--success);
    }

    .sample-tag.missing {
      background: rgba(239, 68, 68, 0.2);
      color: #ef4444;
    }

    .status-bar {
      background: var(--bg-secondary);
      border-top: 1px solid var(--border-color);
      padding: 0.75rem 2rem;
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-size: 0.75rem;
      color: var(--text-muted);
    }

    .status-indicator {
      display: flex;
      align-items: center;
      gap: 0.5rem;
    }

    .status-dot {
      width: 8px;
      height: 8px;
      border-radius: 50%;
      background: var(--success);
    }

    .status-dot.inactive {
      background: var(--warning);
    }

    .instrument-selector,
    .variant-selector {
      display: grid;
      grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
      gap: 0.5rem;
      margin-bottom: 1.5rem;
    }

    .instrument-btn,
    .variant-btn {
      background: var(--bg-tertiary);
      border: 2px solid var(--border-color);
      color: var(--text-secondary);
      padding: 0.75rem 1rem;
      border-radius: 8px;
      cursor: pointer;
      transition: all 0.2s ease;
      font-size: 0.875rem;
      font-weight: 500;
      text-align: center;
    }

    .instrument-btn:hover,
    .variant-btn:hover {
      border-color: var(--accent-primary);
      color: var(--text-primary);
    }

    .instrument-btn.active,
    .variant-btn.active {
      background: var(--accent-primary);
      border-color: var(--accent-primary);
      color: white;
    }

    .instrument-btn.loading,
    .variant-btn.loading {
      opacity: 0.5;
      cursor: wait;
      pointer-events: none;
      position: relative;
    }

    .instrument-btn.loading::after,
    .variant-btn.loading::after {
      content: '⏳';
      position: absolute;
      top: 50%;
      left: 50%;
      transform: translate(-50%, -50%);
      font-size: 1.2rem;
      animation: pulse 1s ease-in-out infinite;
    }

    @keyframes pulse {
      0%, 100% { opacity: 1; }
      50% { opacity: 0.5; }
    }

    @media (max-width: 768px) {
      main {
        padding: 1rem;
      }

      .key {
        width: 55px;
        height: 70px;
      }

      .key-letter {
        font-size: 1.25rem;
      }

      .current-note {
        font-size: 3rem;
      }

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

      header {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
      }
    }

    @keyframes fadeIn {
      from { opacity: 0; transform: translateY(10px); }
      to { opacity: 1; transform: translateY(0); }
    }

    .chord-display, .controls-section, .keyboard-section, .sample-info, .recording-section {
      animation: fadeIn 0.5s ease;
    }

    /* Recording section */
    .recording-section {
      background: var(--bg-secondary);
      border: 1px solid var(--border-color);
      border-radius: 16px;
      padding: 1.5rem;
    }

    .recording-header {
      display: flex;
      justify-content: space-between;
      align-items: center;
      margin-bottom: 1rem;
      flex-wrap: wrap;
      gap: 1rem;
    }

    .recording-header h3 {
      font-size: 0.875rem;
      color: var(--text-muted);
      text-transform: uppercase;
      letter-spacing: 0.1em;
    }

    .recording-controls {
      display: flex;
      gap: 0.5rem;
      flex-wrap: wrap;
    }

    .rec-btn {
      background: var(--bg-tertiary);
      border: 1px solid var(--border-color);
      color: var(--text-secondary);
      padding: 0.5rem 1rem;
      border-radius: 6px;
      cursor: pointer;
      transition: all 0.2s ease;
      font-size: 0.875rem;
      display: flex;
      align-items: center;
      gap: 0.5rem;
    }

    .rec-btn:hover {
      border-color: var(--accent-primary);
      color: var(--text-primary);
    }

    .rec-btn.recording {
      background: rgba(239, 68, 68, 0.2);
      border-color: #ef4444;
      color: #ef4444;
    }

    .rec-icon {
      color: #ef4444;
    }

    .progression-display {
      background: var(--bg-tertiary);
      border-radius: 8px;
      padding: 1rem;
      min-height: 60px;
      display: flex;
      flex-wrap: wrap;
      gap: 0.5rem;
      align-items: center;
    }

    .progression-note {
      background: var(--accent-primary);
      color: var(--bg-primary);
      padding: 0.5rem 0.75rem;
      border-radius: 6px;
      font-weight: 600;
      font-size: 0.875rem;
    }

    .empty-progression {
      color: var(--text-muted);
      font-style: italic;
    }

    /* Export dropdown */
    .export-dropdown {
      position: relative;
      display: inline-block;
    }

    .export-menu {
      display: none;
      position: absolute;
      bottom: 100%;
      right: 0;
      background: var(--bg-tertiary);
      border: 1px solid var(--border-color);
      border-radius: 8px;
      padding: 0.5rem;
      margin-bottom: 0.5rem;
      min-width: 140px;
      z-index: 100;
      box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
    }

    .export-menu.show {
      display: flex;
      flex-direction: column;
      gap: 0.25rem;
    }

    .export-option {
      background: transparent;
      border: none;
      color: var(--text-secondary);
      padding: 0.5rem 0.75rem;
      border-radius: 4px;
      cursor: pointer;
      text-align: left;
      font-size: 0.875rem;
      transition: all 0.2s ease;
    }

    .export-option:hover {
      background: var(--accent-primary);
      color: white;
    }

    /* Generated bass section */
    .generated-section {
      background: var(--bg-secondary);
      border: 1px solid var(--border-color);
      border-radius: 16px;
      padding: 1.5rem;
    }

    .generated-header {
      display: flex;
      justify-content: space-between;
      align-items: center;
      margin-bottom: 1rem;
      flex-wrap: wrap;
      gap: 1rem;
    }

    .generated-header h3 {
      font-size: 0.875rem;
      color: var(--text-muted);
      text-transform: uppercase;
      letter-spacing: 0.1em;
    }

    .lucky-btn {
      background: linear-gradient(135deg, #8b5cf6, #a78bfa);
      border: none;
      color: white;
      padding: 0.6rem 1.2rem;
      border-radius: 8px;
      cursor: pointer;
      font-size: 0.875rem;
      font-weight: 600;
      transition: all 0.2s ease;
      display: flex;
      align-items: center;
      gap: 0.5rem;
    }

    .lucky-btn:hover {
      transform: translateY(-2px);
      box-shadow: 0 4px 15px rgba(139, 92, 246, 0.4);
    }

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

    .generated-controls {
      display: flex;
      gap: 0.5rem;
      flex-wrap: wrap;
      margin-bottom: 1rem;
    }

    .gen-btn {
      background: var(--bg-tertiary);
      border: 1px solid var(--border-color);
      color: var(--text-secondary);
      padding: 0.5rem 1rem;
      border-radius: 6px;
      cursor: pointer;
      transition: all 0.2s ease;
      font-size: 0.875rem;
    }

    .gen-btn:hover {
      border-color: var(--accent-primary);
      color: var(--text-primary);
    }

    .gen-btn.playing {
      background: var(--accent-primary);
      border-color: var(--accent-primary);
      color: white;
    }

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

    .history-nav {
      display: flex;
      align-items: center;
      gap: 0.25rem;
      background: var(--bg-secondary);
      border: 1px solid var(--border-color);
      border-radius: 6px;
      padding: 0.25rem;
    }

    .history-btn {
      padding: 0.25rem 0.5rem;
      font-size: 0.75rem;
      min-width: 32px;
      border: none;
    }

    .history-counter {
      font-size: 0.75rem;
      color: var(--text-muted);
      padding: 0 0.5rem;
      min-width: 60px;
      text-align: center;
    }

    .generated-display {
      background: var(--bg-tertiary);
      border-radius: 8px;
      padding: 1rem;
      min-height: 80px;
      display: flex;
      flex-wrap: wrap;
      gap: 0.5rem;
      align-items: center;
    }

    .generated-note {
      background: #8b5cf6;
      color: white;
      padding: 0.5rem 0.75rem;
      border-radius: 6px;
      font-weight: 600;
      font-size: 0.875rem;
      transition: all 0.15s ease;
    }

    .generated-note.current {
      transform: scale(1.15);
      box-shadow: 0 0 15px rgba(139, 92, 246, 0.6);
    }

    .empty-generated {
      color: var(--text-muted);
      font-style: italic;
    }

    .bar-divider {
      width: 2px;
      height: 30px;
      background: var(--border-color);
      margin: 0 0.25rem;
    }

    /* BPM Control */
    .bpm-control {
      display: flex;
      align-items: center;
      gap: 0.75rem;
      background: var(--bg-tertiary);
      padding: 0.5rem 1rem;
      border-radius: 8px;
      border: 1px solid var(--border-color);
    }

    .bpm-control label {
      font-size: 0.75rem;
      color: var(--text-secondary);
      text-transform: uppercase;
      letter-spacing: 0.05em;
    }

    .bpm-control input[type="range"] {
      width: 80px;
      height: 6px;
      background: var(--bg-primary);
      border-radius: 3px;
      -webkit-appearance: none;
      cursor: pointer;
    }

    .bpm-control input[type="range"]::-webkit-slider-thumb {
      -webkit-appearance: none;
      width: 14px;
      height: 14px;
      background: #8b5cf6;
      border-radius: 50%;
      cursor: pointer;
    }

    .bpm-value {
      font-size: 1rem;
      font-weight: 600;
      color: #a78bfa;
      min-width: 50px;
      width: 55px;
      background: var(--bg-tertiary) !important;
      border: 1px solid var(--border-color);
      border-radius: 4px;
      padding: 0.25rem 0.5rem;
      text-align: center;
      -moz-appearance: textfield;
      -webkit-appearance: none;
      appearance: none;
      color-scheme: dark;
    }

    .bpm-value::-webkit-outer-spin-button,
    .bpm-value::-webkit-inner-spin-button {
      -webkit-appearance: none;
      margin: 0;
    }

    /* Piano Roll Visualization */
    .piano-roll-container {
      background: var(--bg-tertiary);
      border-radius: 8px;
      padding: 0.5rem;
      overflow-x: auto;
      margin-top: 1rem;
    }

    .piano-roll {
      display: flex;
      min-height: 150px;
      position: relative;
    }

    .piano-roll-labels {
      display: flex;
      flex-direction: column;
      min-width: 40px;
      background: var(--bg-secondary);
      border-right: 1px solid var(--border-color);
      position: sticky;
      left: 0;
      z-index: 10;
    }

    .piano-roll-label {
      height: 20px;
      display: flex;
      align-items: center;
      justify-content: flex-end;
      padding-right: 0.5rem;
      font-size: 0.65rem;
      color: var(--text-muted);
      border-bottom: 1px solid var(--border-color);
    }

    .piano-roll-label.sharp {
      background: rgba(0, 0, 0, 0.3);
    }

    .piano-roll-grid {
      flex: 1;
      position: relative;
      min-width: 800px;
    }

    .piano-roll-row {
      height: 20px;
      border-bottom: 1px solid var(--border-color);
      position: relative;
    }

    .piano-roll-row.sharp {
      background: rgba(0, 0, 0, 0.2);
    }

    .piano-roll-bar-line {
      position: absolute;
      top: 0;
      bottom: 0;
      width: 1px;
      background: var(--border-color);
      z-index: 1;
    }

    .piano-roll-bar-line.bar {
      background: rgba(139, 92, 246, 0.4);
      width: 2px;
    }

    .piano-roll-note {
      position: absolute;
      height: 18px;
      top: 1px;
      background: linear-gradient(135deg, #8b5cf6, #a78bfa);
      border-radius: 3px;
      z-index: 5;
      box-shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
      transition: opacity 0.1s ease;
    }

    .piano-roll-note.current {
      background: linear-gradient(135deg, #06b6d4, #22d3ee);
      box-shadow: 0 0 10px rgba(6, 182, 212, 0.5);
    }

    .piano-roll-note.chord {
      background: linear-gradient(135deg, #ec4899, #f472b6);
      box-shadow: 0 1px 3px rgba(236, 72, 153, 0.4);
    }

    .piano-roll-note.chord.current {
      background: linear-gradient(135deg, #06b6d4, #22d3ee);
      box-shadow: 0 0 10px rgba(6, 182, 212, 0.5);
    }

    /* Layer-specific current states for arrangement mode */
    .piano-roll-note[data-layer="bass"].current {
      filter: brightness(1.4);
      box-shadow: 0 0 12px rgba(139, 92, 246, 0.7);
    }

    .piano-roll-note[data-layer="piano"].current {
      filter: brightness(1.4);
      box-shadow: 0 0 12px rgba(236, 72, 153, 0.7);
    }

    /* Piano roll editing states */
    .piano-roll-note {
      cursor: grab;
    }

    .piano-roll-note:hover {
      filter: brightness(1.1);
    }

    .piano-roll-note.dragging {
      cursor: grabbing;
      z-index: 100;
      box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
    }

    .piano-roll-note.selected {
      outline: 2px solid #fff;
      outline-offset: -1px;
      z-index: 15;
    }

    .piano-roll-grid {
      cursor: crosshair;
    }

    .piano-roll-playhead {
      position: absolute;
      top: 0;
      bottom: 0;
      width: 2px;
      background: #ef4444;
      z-index: 20;
      box-shadow: 0 0 8px rgba(239, 68, 68, 0.6);
      display: none;
    }

    .piano-roll-playhead.active {
      display: block;
    }

    .piano-roll-bar-numbers {
      display: flex;
      background: var(--bg-secondary);
      border-bottom: 1px solid var(--border-color);
    }

    .piano-roll-bar-number {
      text-align: left;
      font-size: 0.65rem;
      color: var(--text-muted);
      padding: 0.25rem 0.5rem;
      border-right: 1px solid var(--border-color);
      box-sizing: border-box;
      flex-shrink: 0;
    }

    .empty-piano-roll {
      display: flex;
      align-items: center;
      justify-content: center;
      min-height: 150px;
      color: var(--text-muted);
      font-style: italic;
    }

    /* Loop toggle */
    .loop-toggle {
      display: flex;
      align-items: center;
      gap: 0.5rem;
      background: var(--bg-tertiary);
      padding: 0.5rem 0.75rem;
      border-radius: 6px;
      border: 1px solid var(--border-color);
      cursor: pointer;
      transition: all 0.2s ease;
    }

    .loop-toggle:hover {
      border-color: #8b5cf6;
    }

    .loop-toggle.active {
      background: rgba(139, 92, 246, 0.2);
      border-color: #8b5cf6;
    }

    .loop-toggle input {
      display: none;
    }

    .loop-toggle .loop-icon {
      font-size: 1rem;
    }

    .loop-toggle span {
      font-size: 0.875rem;
      color: var(--text-secondary);
    }

    .loop-toggle.active span {
      color: #a78bfa;
    }

    /* Drums toggle */
    .drums-toggle {
      display: flex;
      align-items: center;
      gap: 0.5rem;
      background: var(--bg-tertiary);
      padding: 0.5rem 0.75rem;
      border-radius: 6px;
      border: 1px solid var(--border-color);
      cursor: pointer;
      transition: all 0.2s ease;
    }

    .drums-toggle:hover {
      border-color: #ec4899;
    }

    .drums-toggle.active {
      background: rgba(236, 72, 153, 0.2);
      border-color: #ec4899;
    }

    .drums-toggle input {
      display: none;
    }

    .drums-toggle .drums-icon {
      font-size: 1rem;
    }

    .drums-toggle span {
      font-size: 0.875rem;
      color: var(--text-secondary);
    }

    .drums-toggle.active span {
      color: #ec4899;
    }

    /* Chord Progression Section */
    .chord-progression-section {
      background: var(--bg-secondary);
      border: 1px solid var(--border-color);
      border-radius: 16px;
      padding: 1.5rem;
      margin-bottom: 1rem;
    }

    .chord-progression-section h4 {
      font-size: 0.875rem;
      color: var(--text-muted);
      text-transform: uppercase;
      letter-spacing: 0.1em;
      margin-bottom: 1rem;
      text-align: center;
    }

    .chord-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 1rem;
      margin-bottom: 1rem;
    }

    @media (max-width: 768px) {
      .chord-grid {
        grid-template-columns: repeat(2, 1fr);
      }
    }

    .chord-bar {
      display: flex;
      flex-direction: column;
      gap: 0.5rem;
    }

    .chord-bar label {
      font-size: 0.75rem;
      color: var(--text-secondary);
      text-transform: uppercase;
      letter-spacing: 0.05em;
    }

    .chord-bar select {
      background: var(--bg-tertiary);
      border: 1px solid var(--border-color);
      color: var(--text-primary);
      padding: 0.6rem 0.75rem;
      border-radius: 6px;
      font-size: 0.875rem;
      cursor: pointer;
      transition: all 0.2s ease;
    }

    .chord-bar select:hover {
      border-color: var(--accent-primary);
    }

    .chord-bar select:focus {
      outline: none;
      border-color: var(--accent-primary);
      box-shadow: 0 0 0 2px var(--accent-glow);
    }

    .chord-presets {
      display: flex;
      flex-wrap: wrap;
      gap: 0.5rem;
      justify-content: center;
    }

    .chord-preset-btn {
      background: var(--bg-tertiary);
      border: 1px solid var(--border-color);
      color: var(--text-secondary);
      padding: 0.5rem 1rem;
      border-radius: 6px;
      cursor: pointer;
      transition: all 0.2s ease;
      font-size: 0.75rem;
      font-weight: 500;
    }

    .chord-preset-btn:hover {
      border-color: #06b6d4;
      color: #06b6d4;
      background: rgba(6, 182, 212, 0.1);
    }

    .chord-preset-btn:active {
      transform: scale(0.95);
    }

    /* Collapsible Section Styles */
    .collapsible-section {
      margin: 1rem 0;
    }

    .collapsible-toggle {
      width: 100%;
      background: var(--bg-tertiary);
      border: 1px solid var(--border-color);
      border-radius: 8px;
      padding: 0.75rem 1rem;
      color: var(--text-secondary);
      font-size: 0.875rem;
      font-weight: 500;
      cursor: pointer;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 0.5rem;
      transition: all 0.2s ease;
    }

    .collapsible-toggle:hover {
      background: var(--bg-secondary);
      border-color: var(--accent-primary);
      color: var(--text-primary);
    }

    .toggle-arrow {
      font-size: 0.75rem;
      transition: transform 0.3s ease;
    }

    .collapsible-toggle.collapsed .toggle-arrow {
      transform: rotate(-90deg);
    }

    .collapsible-content {
      overflow: hidden;
      transition: max-height 0.3s ease, opacity 0.3s ease, visibility 0.3s ease;
      max-height: 2000px;
      opacity: 1;
      visibility: visible;
    }

    .collapsible-content.collapsed {
      max-height: 0;
      opacity: 0;
      padding: 0;
      margin: 0;
      visibility: hidden;
      pointer-events: none;
    }