<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css"> <script src="//maxcdn.bootstrapcdn.com/bootstrap/4.0.0/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 ----------> <section class="main-content py-5 mb-5" id="main-content"> <div class="container"> <div class="row"> <div class="col-md-8 "> <div class="card-body bg-light border"> column8 </div> </div> <div class="col-md-4 "> <div class="card bg-light"> <div class="card-body"> column4 </div> </div> </div> </div> </div> </section>