.overlay {
    display: none;
    position: fixed;
    z-index: 1000;
    top: 0;
    left: 0;
    height: 100%;
    width: 100%;
    background: rgba( 0, 0, 0,1) url(loader.gif) 50% 50% no-repeat;
    -webkit-opacity: 0.6;
    -khtml-opacity: 0.6;
    -moz-opacity: 0.6;
    -ms-opacity: 0.6;
    -o-opacity: 0.6;
    -ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=60)";
    filter: alpha(opacity=60);
    opacity: 0.6;
}

body.loading {
    overflow: hidden;
}
body.loading .overlay {
    display: block;
}