.loader {
    display: none; 
    position: fixed; 
    top: 0; 
    left: 0; 
    height: 100%; 
    width: 100%; 
    background: rgba( 255, 255, 255, .8 ) url('../img/ajax-loader.gif') 50% 50% no-repeat;
    z-index: 99999;
}