<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css"> <script src="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script> <script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script> <!------ Include the above in your HEAD tag ----------> <div class="container"> <div class="row"> <div class="text-center"> <a href="#">Hover me</a> </div> </div> </div>

a { color: #333333; text-decoration: none; position: relative; } a:before { content: ""; background-color: rgba(22, 144, 179, 0.2); width: 100%; height: 5px; position: absolute; bottom: -10px; left: 0; visibility: hidden; -webkit-transform: scaleX(0); transform: scaleX(0); -webkit-transition: all 0.3s ease-in-out 0s; transition: all 0.3s ease-in-out 0s; } a:hover { color: #137e9c; text-decoration: none; } a:hover:before { visibility: visible; -webkit-transform: scaleX(1); transform: scaleX(1); }