<link href="//netdna.bootstrapcdn.com/bootstrap/3.0.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css"> <script src="//netdna.bootstrapcdn.com/bootstrap/3.0.0/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"> <div class="row"> <div id="holder"> <div id="mask"></div> </div> </div> </div>

#holder { border: 1px solid #000; height: 200px; width: 200px; position:relative; margin:10px; } #mask { position: absolute; top:-1px; left:1px; width:50%; height: 1px; background-color:#fff; }