.esperar {
    position: fixed;
    left: 0px;
    top: 0px;
    width: 100%;
    height: 100%;
    z-index: 9999;
    background: url('../Imagenes/load3.GIF') 50% 50% no-repeat rgb(249,249,249);
    opacity: .5;    
}

#back{
      position: absolute;
      top:0;
      left:0;
      width:100%;
      height:100vh;
      background: url(../Imagenes/loby.1.webp);      
      background-size:cover;
      overflow:hidden;
      z-index: -1;

}