<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"> <h2>Create your snippet's HTML, CSS and Javascript in the editor tabs</h2> </div> </div>

background: linear-gradient(90deg, rgba(0, 0, 0, 1) 15%, rgba(148, 0, 211, 1) 25%, rgba(75, 0, 130, 1) 30%, rgba(0, 0, 255, 1) 35%, rgba(0, 255, 0, 1) 50%, rgba(255, 255, 0, 1) 55%, rgba(255, 127, 0, 1) 70%, rgba(255, 0, 0, 1) 75%, rgba(0, 0, 0, 1) 85%);