<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>
<nav class="navbar navbar-expand-lg">
<ul class="navbar-nav">
<li class="active">
<a href="#" class="nav-link">Home</a>
</li>
<li class="nav-item">
<a href="#" class="nav-link">Product</a>
</li>
<li class="nav-item">
<a href="#" class="nav-link">Contact Us</a>
</li>
</ul>
</div>
</nav>