#cortina{
    position: absolute;
    position: fixed;
    z-index: 1050;
    background-color: #ffffff;
    opacity: 0.3;
    background-repeat: no-repeat;
    background-position: center;
    padding: 17 px;
    background-image: url(../img/loader2.gif);
    width: 100%;
    height: 100%;
}