.g-mask{position:relative}.g-mask_cover{position:absolute;left:0;top:0;background:rgba(0,0,0,.5);width:100%;height:100%;opacity:0;filter:alpha(opacity=0);transition:opacity 300ms;-webkit-transition:opacity 300ms}.g-mask:hover .g-mask_cover{opacity:1;filter:alpha(opacity=100)}