JSFiddle - React, Tailwind, and code Playground
HTML
<div id='main'>
<div id='rightP'>
<div id='theframe' class='phn'>
<iframe id='themagic' src="http://fiddle.jshell.net/tV46k/2/show/">
</iframe>
</div>
</div>
</div>
CSS
iframe {width:320px;height:528px;margin:0;padding:0;position:absolute;top:0;left:0;
JavaScript
function doThis() {
var myIframe = document.getElementById("themagic");
var content = myIframe.contentWindow.document.getElementById('leOutput');
var btn = myIframe.contentWindow.document.createElement('button');
btn.innerHTML = 'Click Me';
content.appendChild(btn);
}
window.onload = doThis();