.element{position:relative}.element:before{content:"";position:absolute;width:0;height:2px;bottom:0;left:0;background-color:#fff;visibility:hidden;transition:all .3s ease-in-out}.element:hover:before{z-index:50;width:100%;visibility:visible}@keyframes slideDown{0%{opacity:0;transform:translateY(-10%)}to{opacity:1;transform:translateY(0)}}.submenu{position:absolute;top:47px;animation:slideDown .5s ease-in-out forwards}