#back{
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url(../img/plantilla/back.jpg);
    background-size: cover;
    overflow: hidden;
    z-index: -1;
    opacity: 0.8;

}



.custom-file-label::after {
    content: "Seleccionar" !important; }