.preloader{
    position: fixed;
    top:0;
    left:0;
    bottom: 0;
    right: 0;
    background: #fff;
    z-index: 99999;
}
 
.preloader .preloader-gif{
    display: block;
    width: 80px;
    height: 80px;
    position: absolute;
    top: 50%;
    left: 50%;
    margin: -40px 0 0 -40px;
    background: url('../images/preloader.gif') no-repeat;   
}