JSFiddle - React, Tailwind, and code Playground

HTML

<div id="selector">SELECTOR</div>
<iframe id="iframe" src="http://fiddle.jshell.net/x3a71jsv/1/show/" allowfullscreen="allowfullscreen" frameborder="0"></iframe>

CSS

#selector {
     position: absolute;
     top: 150px;
     left: 150px;
     width: 250px;
     height: 250px;
     -webkit-box-shadow: 0px 0px 0px 5px yellow;
     -moz-box-shadow: 0px 0px 0px 5px yellow;
     box-shadow: 0px 0px 0px 5px yellow;
 }
 #iframe {
     width: 500px;
     height: 500px;
     border: none;
 }