button.add_to_cart_button.loading:after{
    position:absolute;
    top:0;
    left:0;
    width:100%;
    height:100%;
    font-family:"Glyphicons Halflings";
    content: "e031";
    background: rgba( 255, 255, 255, 0.7 );
    text-align:center;
    line-height:34px;
}