.divindex {
        position: absolute;
        width: 600px;
        
        z-index: 15;
        top: 50%;
        left: 50%;
        margin: -150px 0 0 -300px;
    }


@media (max-width: 400px)
{
 .divindex {
        position: block;
        width: auto;
        
        z-index: 15;
        top: 30%;
        left: auto;
        margin: auto;
    }


}