.button{position:relative;padding:10px 20px;color:#374151;transition:color .3s ease;z-index:0;border-radius:5px;border:2px solid orange}.button span{position:absolute;top:0;left:0;height:100%;width:2px;background-color:orange;transition:width .3s ease;z-index:-1;font-size:medium}.button:hover{color:#fff}.button:hover span{width:100%}