#carga{
    display: none;
}

#fondo-carga{  
    z-index: 3;
    background: #fff;
    position: fixed;
    opacity: .75;
    filter: alpha(opacity=75); 
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

#spinner{   
    z-index: 4;
    position: fixed;   
    top: 50%;
    left: 50%;    
}