JSFiddle - React, Tailwind, and code Playground

HTML

<body><div class="uno"><img src="https://www.google.com.ar/images/srpr/logo3w.png" height="47"  /></div>
<iframe class="dos" src="http://www.forosdelweb.com" height="100%" width="100%" frameborder="0" marginheight="0" marginwidth="0" />
</body>

CSS

body, html
{
    width:100%;
    height:100%;
}
.uno
{
    position:absolute;
    top:100px;
}