<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>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/gh/fancyapps/fancybox@3.5.7/dist/jquery.fancybox.min.css" />
<script src="https://cdn.jsdelivr.net/gh/fancyapps/fancybox@3.5.7/dist/jquery.fancybox.min.js"></script>
<div class="container">
<div class="row">
<a class="fancybox" data-fancybox href="http://samplepdf.com/sample.pdf">Open pdf</a>
</div>
</div>
<script>
$(".fancybox").fancybox({
width : 900,
height : 300,
type :'iframe'
});
</script>
