:root {
            --bg-color: #0f172a;
            --card-bg: #1e293b;
            --accent-blue: #38bdf8;
            --accent-glow: #0284c7;
            --text-main: #f8fafc;
            --text-sub: #94a3b8;
            --danger: #ef4444;
            --success: #22c55e;
        }

        * {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
            font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
        }

        body {
            background-color: var(--bg-color);
            color: var(--text-main);
            min-height: 100vh;
            display: flex;
            flex-direction: column;
            align-items: center;
            padding: 20px;
        }

        header {
            text-align: center;
            margin-bottom: 24px;
        }

        header h1 {
            font-size: 2rem;
            color: var(--accent-blue);
            margin-bottom: 8px;
        }

        header p {
            color: var(--text-sub);
            font-size: 0.95rem;
        }

        .container {
            width: 100%;
            max-width: 500px;
            display: flex;
            flex-direction: column;
            gap: 20px;
        }

        .card {
            background: var(--card-bg);
            border-radius: 16px;
            padding: 20px;
            box-shadow: 0 10px 25px -5px rgba(0,0,0,0.3);
            border: 1px solid rgba(255,255,255,0.05);
        }

        .visualizer-container {
            position: relative;
            height: 180px;
            display: flex;
            justify-content: center;
            align-items: center;
            overflow: hidden;
            border-radius: 12px;
            background: #090d16;
        }

        canvas {
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
        }

        .speaker-icon {
            width: 80px;
            height: 80px;
            border-radius: 50%;
            background: #334155;
            border: 4px solid var(--accent-blue);
            display: flex;
            align-items: center;
            justify-content: center;
            z-index: 2;
            transition: transform 0.05s ease;
            box-shadow: 0 0 20px rgba(56, 189, 248, 0.3);
        }

        .speaker-icon svg {
            width: 40px;
            height: 40px;
            fill: var(--text-main);
        }

        .pulsing {
            animation: pulse-ring 0.5s infinite alternate;
        }

        @keyframes pulse-ring {
            0% { box-shadow: 0 0 15px var(--accent-glow); }
            100% { box-shadow: 0 0 35px var(--accent-blue); }
        }

        .presets {
            display: grid;
            grid-template-columns: repeat(2, 1fr);
            gap: 12px;
        }

        .btn {
            background: #334155;
            color: var(--text-main);
            border: none;
            padding: 14px;
            border-radius: 12px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.2s;
            display: flex;
            flex-direction: column;
            align-items: center;
            gap: 4px;
        }

        .btn span {
            font-size: 0.75rem;
            color: var(--text-sub);
            font-weight: normal;
        }

        .btn:hover {
            background: #475569;
        }

        .btn.active {
            background: var(--accent-glow);
            border: 2px solid var(--accent-blue);
        }

        .btn-primary {
            background: var(--accent-blue);
            color: #0f172a;
            font-size: 1.1rem;
            padding: 16px;
            width: 100%;
            border-radius: 12px;
            border: none;
            font-weight: 700;
            cursor: pointer;
            margin-top: 10px;
        }

        .btn-primary:hover {
            opacity: 0.9;
        }

        .controls {
            display: flex;
            flex-direction: column;
            gap: 16px;
            margin-top: 12px;
        }

        .control-group {
            display: flex;
            flex-direction: column;
            gap: 6px;
        }

        .control-group label {
            display: flex;
            justify-content: space-between;
            font-size: 0.9rem;
            color: var(--text-sub);
        }

        input[type="range"] {
            width: 100%;
            accent-color: var(--accent-blue);
        }

        .instructions {
            font-size: 0.85rem;
            color: var(--text-sub);
            line-height: 1.5;
        }

        .instructions ol {
            padding-left: 18px;
            margin-top: 8px;
        }

        .instructions li {
            margin-bottom: 6px;
        }