.Underlay{position:fixed;top:0;left:0;width:100%;height:100%;background:rgba(0,0,0,.5);z-index:40;overflow-y:auto;cursor:pointer;visibility:hidden;opacity:0;-webkit-transition:opacity .2s ease-out,visibility .2s ease-out;transition:opacity .2s ease-out,visibility .2s ease-out}.Underlay.visible{visibility:visible;opacity:1}