#loading_box {
    width: 100%;
    height: 100%;
    background: #FFF;
    opacity: 0.8;
    position: fixed;
    top: 0;
    left: 0;
    z-index: 1000;
}
 
#loading_box img {
    position: absolute;
    top: 50%;
    left: 50%;
    margin: -40px 0 0 -40px;
    width: auto;
}