:root {
            --primary: #0f172a;
            --accent: #3b82f6;
            --bg: #ffffff;
        }

        body {
            font-family: 'Inter', system-ui, -apple-system, sans-serif;
            background-color: var(--bg);
            display: flex;
            justify-content: center;
            align-items: center;
            
            margin: 0;
            padding: 15px; /* Espacio para móviles */
        }

        .card {
            background: white;
            padding: 2rem;
            border-radius: 1rem;
            box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.1);
            width: 100%;
            max-width: 550px;
            box-sizing: border-box;
        }

        .header { text-align: center; margin-bottom: 1.5rem; }
        .header h2 { margin: 0; color: var(--primary); font-size: 1.5rem; }

        /* Escala Responsiva con CSS Grid */
        .grid-5 {
            display: grid;
            grid-template-columns: repeat(5, 1fr);
            border: 2px solid #e2e8f0;
            border-radius: 0.75rem;
            overflow: hidden;
            margin: 1.5rem 0 0.5rem 0;
        }

        .opcion {
            position: relative;
            text-align: center;
            padding: 1.5rem 0;
            cursor: pointer;
            transition: all 0.2s;
            border-right: 1px solid #e2e8f0;
            background: #fff;
        }

        .opcion:last-child { border-right: none; }
        .opcion input { position: absolute; opacity: 0; width: 100%; height: 100%; top: 0; left: 0; cursor: pointer; margin: 0; }
        
        .opcion:hover { background: #f8fafc; }
        
        /* Efecto de selección moderna */
        .opcion:has(input:checked) {
            background: var(--accent);
            color: white;
            border-color: var(--accent);
        }

        .number { font-size: 1.25rem; font-weight: 700; }

        /* Etiquetas de texto */
        .labels {
            display: flex;
            justify-content: space-between;
            font-size: 0.8rem;
            color: #64748b;
            font-weight: 500;
            margin-bottom: 2rem;
        }

        .btn-grabar {
            background: var(--primary);
            color: white;
            border: none;
            width: 100%;
            padding: 1rem;
            border-radius: 0.6rem;
            font-size: 1rem;
            font-weight: 600;
            cursor: pointer;
            transition: transform 0.1s, background 0.2s;
        }

        .btn-grabar:active { transform: scale(0.98); }

        .alert {
            padding: 1rem;
            margin-bottom: 1.5rem;
            border-radius: 0.5rem;
            text-align: center;
            font-size: 0.9rem;
        }
        .alert-success { background: #dcfce7; color: #166534; border: 1px solid #bbf7d0; }

        /* --- MEDIA QUERIES PARA MÓVILES --- */
        @media (max-width: 480px) {
            .card { padding: 1.5rem; }
            .header h2 { font-size: 1.25rem; }
            .opcion { padding: 1.2rem 0; }
            .number { font-size: 1.1rem; }
            .labels { font-size: 0.7rem; }
        }