body {
            margin: 0;
            overflow: hidden;
            background-color: #111;
            font-family: 'Segoe UI', sans-serif;
            color: white;
            touch-action: none;
            /* Empêche le scroll sur mobile pour mieux jouer */
        }

        canvas {
            display: block;
            cursor: crosshair;
        }

        /* UI Panel */
        #ui-panel {
            position: absolute;
            top: 20px;
            left: 20px;
            width: 300px;
            background: rgba(0, 0, 0, 0.85);
            padding: 20px;
            border-radius: 12px;
            border-left: 4px solid #fff;
            box-shadow: 0 4px 15px rgba(0, 0, 0, 0.5);
            pointer-events: auto;
            user-select: none;
        }

        h1 {
            margin: 0 0 15px 0;
            font-size: 1.2rem;
            text-transform: uppercase;
            letter-spacing: 2px;
            color: #fff;
            border-bottom: 1px solid #444;
            padding-bottom: 10px;
        }

        .control-group {
            margin-bottom: 15px;
        }

        label {
            display: flex;
            justify-content: space-between;
            font-size: 0.9rem;
            color: #aaa;
            margin-bottom: 5px;
        }

        input[type="range"] {
            width: 100%;
            accent-color: #fff;
            height: 4px;
            background: #444;
            border-radius: 2px;
            outline: none;
            -webkit-appearance: none;
        }

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

        .hint {
            font-size: 0.8rem;
            color: #666;
            font-style: italic;
            margin-top: 5px;
        }

        /* Back Button */
        .back-btn {
            position: absolute;
            top: 20px;
            right: 20px;
            color: #aaa;
            text-decoration: none;
            background: rgba(255, 255, 255, 0.1);
            padding: 8px 16px;
            border-radius: 20px;
            font-size: 0.9rem;
            transition: all 0.3s;
        }

        .back-btn:hover {
            background: rgba(255, 255, 255, 0.2);
            color: white;
        }

        #spectrum-legend {
            display: flex;
            height: 4px;
            width: 100%;
            margin-top: 5px;
            border-radius: 2px;
            background: linear-gradient(to right, red, orange, yellow, green, blue, indigo, violet);
        }