.ajax-loader {
   position: fixed;
   top: 0;
   right: 0;
   bottom: 0;
   left: 0;
   z-index: 1100;
   background: #fff url('../images/loading_bg.jpg') no-repeat center center;
   opacity: 1;
   background-size: 30%;
}

.ajax-loader > img {
   position: absolute;
   left: 50%;
   bottom: 50%;
   margin-left: -32px; /* -1 * image width / 2 */
   margin-top: -32px; /* -1 * image height / 2 */
   display: block;
}