<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="//code.jquery.com/jquery-1.11.1.min.js"></script> <!------ Include the above in your HEAD tag ----------> <div class="container"> <nav class="navbar navbar-expand-lg navbar-light bg-warning"> <div class="collapse navbar-collapse" id="navbarSupportedContent"> <ul class="navbar-nav ml-auto topnav"> <li class="nav-item dropdown"> <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false"> Terms And Conditions </a> <div class="dropdown-menu" aria-labelledby="navbarDropdown"> <a class="dropdown-item" href="#">Calvin Klein</a> <a class="dropdown-item" href="#">PVH Brands</a> <a class="dropdown-item" href="#">PVH Italy</a> <a class="dropdown-item" href="#">PVH Norge</a> <a class="dropdown-item" href="#">Tommy Hilfiger</a> </div> </li> </ul> </div> </div> </nav> </div>

.topnav a:hover { border-bottom: 3px solid red; }