div.ajax-loading
{
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    background-color: #ddd;
    opacity:0.9;
}
div.ajax-loading img
{
    position: absolute;
    left: 50%;
    top: 50%;
    margin-left: -109px;
    margin-top: -9px;
    display: block;
}