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

        body {
            font-family: 'Arial', sans-serif;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            min-height: 100vh;
            display: flex;
            justify-content: center;
            align-items: flex-start;
            padding: 15px;
            padding-top: 20px;
        }

        .container {
            background: rgba(255, 255, 255, 0.95);
            backdrop-filter: blur(10px);
            border-radius: 20px;
            padding: 25px;
            box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
            max-width: 1200px;
            width: 100%;
        }

        h1 {
            text-align: center;
            color: #333;
            margin-bottom: 20px;
            font-size: 2.2em;
            background: linear-gradient(45deg, #667eea, #764ba2);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
        }

        .audio-section {
            background: #f8f9fa;
            border-radius: 12px;
            margin-bottom: 10px;
            text-align: center;
        }

        .audio-section h2 {
            color: #333;
            margin-bottom: 15px;
            font-size: 1.5em;
        }

        .audio-controls {
            display: flex;
            gap: 8px;
            justify-content: center;
            align-items: center;
            flex-wrap: wrap;
            margin-bottom: 10px;
        }

        .audio-info {
            background: white;
            padding: 15px;
            border-radius: 10px;
            margin-bottom: 15px;
            box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
        }

        .audio-info h3 {
            color: #667eea;
            margin-bottom: 10px;
            font-size: 1.2em;
        }

        .current-track {
            font-weight: bold;
            color: #333;
            margin-bottom: 10px;
            font-size: 1.1em;
        }

        .track-details {
            border-radius: 8px;
            padding: 16px;
            margin-bottom: 15px;
            background: white;
        }

        .track-title {
            font-weight: bold;
            color: #333;
            font-size: 1.1em;
            text-align: center;
            margin-bottom: 8px;
        }

        .track-tempo {
            color: #555;
            font-size: 0.95em;
            font-weight: bold;
            text-align: left;
            margin-bottom: 8px;
        }

        .track-chords-container {
            margin-top: 10px;
        }

        .chord-table {
            width: 100%;
            border-collapse: collapse;
            margin-top: 5px;
        }

        .chord-table td {
            padding: 4px 8px;
            border: 1px solid #ddd;
            text-align: center;
            font-size: 0.9em;
        }

        .chord-names td {
            background: #f8f9fa;
            font-weight: bold;
            color: #333;
        }

        .chord-functions td {
            background: #e9ecef;
            color: #555;
        }

        .scale-hints {
            text-align: left;
            padding-top: 15px;
        }

        .track-list {
            max-height: 500px;
            overflow-y: auto;
            margin-top: 15px;
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
            gap: 12px;
            padding: 5px;
        }

        .track-item {
            background: white;
            padding: 12px;
            margin-bottom: 0;
            border-radius: 6px;
            cursor: pointer;
            transition: all 0.2s ease;
            border: 2px solid transparent;
            display: flex;
            flex-direction: column;
            justify-content: center;
            text-align: left;
        }

        .track-item:hover {
            background: #e9ecef;
            transform: translateX(5px);
        }

        .track-item.active {
            background: #d4edda;
            border-color: #28a745;
        }

        .track-name {
            font-weight: bold;
            color: #333;
            margin-bottom: 4px;
        }

        .track-meta {
            font-size: 0.85em;
            color: #666;
        }

        .scale-category {
            margin-bottom: 10px;
        }

        .scale-category h4 {
            color: #333;
            margin-bottom: 5px;
            font-size: 1em;
        }

        .scale-list {
            color: #555;
            font-size: 0.9em;
            line-height: 1.4;
            margin-left: 10px;
        }

        .controls {
            display: flex;
            gap: 15px;
            margin-bottom: 15px;
            align-items: center;
            justify-content: center;
            flex-wrap: wrap;
        }

        .control-group {
            display: flex;
            align-items: center;
            gap: 10px;
        }

        .button-group {
            display: flex;
            gap: 10px;
            flex-wrap: wrap;
            justify-content: center;
            align-items: center;
        }

        /* Container for mutually exclusive buttons to occupy the same space */
        .button-stack {
            display: inline-flex;
            gap: 10px;
            align-items: center;
            justify-content: center;
        }

        .play-pause-stack {
            display: inline-grid;
            grid-template-areas: "stack";
            align-items: center;
            justify-items: center;
        }

        .play-pause-stack button {
            grid-area: stack;
        }

        .play-pause-stack button[style*="display: none"],
        .button-stack button[style*="display: none"] {
            display: none !important;
        }

        label {
            font-weight: bold;
            color: #555;
            font-size: 14px;
        }

        input[type="range"] {
            padding: 0;
            height: 8px;
            -webkit-appearance: none;
            background: #e9ecef;
            border-radius: 4px;
            border: none;
            cursor: pointer;
        }

        input[type="range"]::-webkit-slider-thumb {
            -webkit-appearance: none;
            width: 16px;
            height: 16px;
            background: #667eea;
            border-radius: 50%;
            cursor: pointer;
            transition: background 0.3s;
        }

        input[type="range"]::-webkit-slider-thumb:hover {
            background: #764ba2;
        }

        input, button, select {
            padding: 8px 12px;
            border: none;
            border-radius: 6px;
            font-size: 13px;
        }

        input, select {
            background: #f8f9fa;
            border: 2px solid #e9ecef;
            transition: border-color 0.3s;
        }

        input:focus, select:focus {
            outline: none;
            border-color: #667eea;
        }

        select {
            cursor: pointer;
        }

        button {
            background: linear-gradient(45deg, #667eea, #764ba2);
            color: white;
            cursor: pointer;
            transition: transform 0.2s, box-shadow 0.2s;
            font-weight: bold;
        }

        button:hover {
            transform: translateY(-2px);
            box-shadow: 0 10px 20px rgba(0, 0, 0, 0.2);
        }

        button:disabled {
            background: #ccc;
            cursor: not-allowed;
            transform: none;
            box-shadow: none;
        }

        .audio-button {
            background: linear-gradient(45deg, #28a745, #20c997);
        }

        .display-area {
            margin-bottom: 20px;
        }

        .current-prompt {
            background: linear-gradient(135deg, #667eea, #764ba2);
            color: white;
            padding: 15px;
            border-radius: 12px;
            text-align: center;
            margin-bottom: 10px;
            box-shadow: 0 8px 25px rgba(0, 0, 0, 0.2);
            transition: all 0.3s ease;
        }

        .current-prompt h2 {
            font-size: 1em;
            margin-bottom: 8px;
            opacity: 0.9;
        }

        .current-prompt .prompt-text {
            font-size: 1.4em;
            font-weight: bold;
            margin-bottom: 5px;
        }

        .progress-bar {
            width: 100%;
            height: 6px;
            background: #e9ecef;
            border-radius: 3px;
            overflow: hidden;
            margin-bottom: 15px;
        }

        .progress-fill {
            height: 100%;
            background: linear-gradient(45deg, #667eea, #764ba2);
            width: 0%;
            transition: width 0.1s linear;
        }

        @media (max-width: 600px) {
            .track-list {
                grid-template-columns: 1fr;
            }

            .exercise-items {
                grid-template-columns: 1fr;
            }

            .container {
                padding: 15px;
                max-width: 100%;
            }
            
            h1 {
                font-size: 1.8em;
                margin-bottom: 20px;
            }
            
            .controls, .audio-controls {
                flex-direction: row;
                gap: 10px;
                margin-bottom: 15px;
                justify-content: center;
            }
            
            .control-group {
                width: 100%;
                justify-content: space-between;
            }

            .button-group, .audio-controls {
                width: 100%;
                justify-content: center;
                flex-wrap: wrap;
            }

            .button-group button, .audio-controls button {
                flex: 0 1 auto;
                min-width: 80px;
                font-size: 12px;
                padding: 8px 12px;
                margin: 2px;
            }

            .current-prompt .prompt-text {
                font-size: 1.4em;
            }
        }

        .fade-in {
            animation: fadeIn 0.5s ease-in;
        }

        @keyframes fadeIn {
            from { opacity: 0; transform: translateY(20px); }
            to { opacity: 1; transform: translateY(0); }
        }

        /* Section Toggle Styles */
        .section-toggle {
            background: #f8f9fa;
            border-radius: 15px;
            padding: 15px;
            margin-bottom: 15px;
            text-align: center;
        }

        .section-toggle h2 {
            color: #333;
            margin-bottom: 15px;
            font-size: 1.5em;
        }

        .toggle-controls {
            display: flex;
            justify-content: center;
            gap: 15px;
            align-items: center;
        }

        .toggle-controls label {
            display: flex;
            align-items: center;
            cursor: pointer;
            font-size: 1em;
            color: #555;
            padding: 8px 12px;
            border-radius: 8px;
            transition: all 0.3s ease;
            background: rgba(255, 255, 255, 0.7);
            border: 2px solid transparent;
        }

        .toggle-controls label:hover {
            background: rgba(255, 255, 255, 0.9);
            transform: translateY(-2px);
        }

        .toggle-controls input[type="radio"] {
            margin-right: 8px;
            transform: scale(1.2);
        }

        .toggle-controls input[type="radio"]:checked + span {
            font-weight: bold;
        }

        .toggle-controls label:has(input:checked) {
            background: linear-gradient(45deg, #667eea, #764ba2);
            color: white;
            border: 2px solid #667eea;
        }

        /* Exercise Section Styles */
        .exercise-list {
            display: flex;
            flex-direction: column;
            gap: 20px;
        }

        .exercise-category {
            margin-bottom: 25px;
            background: rgba(255, 255, 255, 0.8);
            border-radius: 10px;
            padding: 15px;
            height: 100%;
        }

        .exercise-category h3 {
            color: #333;
            margin-bottom: 10px;
            font-size: 1.3em;
            padding-bottom: 8px;
            border-bottom: 2px solid #667eea;
        }

        .exercise-items {
            list-style: none;
            padding: 0;
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
            gap: 10px;
        }

        .exercise-item {
            padding: 8px 12px;
            margin: 0;
            background: rgba(102, 126, 234, 0.1);
            border-radius: 8px;
            border-left: 4px solid #667eea;
            transition: all 0.3s ease;
            display: flex;
            align-items: center;
            height: 100%;
        }

        .exercise-item:hover {
            background: rgba(102, 126, 234, 0.2);
            transform: translateX(5px);
        }

        .content-section {
            animation: fadeIn 0.5s ease-in;
        }