#preloader {
    position: absolute;
    z-index: 1001;
    width: 375px;
    max-width: 90%;
    height: 132px;
    background: url(/images/loader.gif) no-repeat 50%;
    background-size: contain;
    top: calc(50% - 50px);
    left: calc(50% - 50px);
}