ul li a{color:#272727}ul li .lin{position:relative;padding:10px;margin:0 10px;transition:all .5s}ul li .lin:before{left:12px;bottom:12px;border-left:1px solid #272727;border-bottom:1px solid #272727}ul li .lin:after,ul li .lin:before{content:"";position:absolute;transform:translateY(-50%);width:5px;height:5px;opacity:0;transition:all .5s}ul li .lin:after{right:12px;top:12px;border-right:1px solid #272727;border-top:1px solid #272727}ul li .lin:hover:before{opacity:1;left:0;bottom:0}ul li .lin:hover:after{opacity:1;right:0;top:0}ul li .lin.active:after,ul li .lin.active:before{opacity:1}ul li .lin.active:before{left:0;bottom:0}ul li .lin.active:after{right:0;top:0}