#canvasFirma{
    width: 100%;
    aspect-ratio: 5 / 2;
    border: 2px dashed #4C8000;
    border-radius: 10px;
    background: white;
    touch-action: none;
}
.firma-preview {
    width: 100%;
    max-width: 500px;
    height: auto;
    border: 1px solid #ddd;
    background: #fff;
    display: block;
    margin: auto;
}