JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<iframe id="forPostyouradd" src="https://rc.air-hamburg.de""></iframe>

CSS

iframe{
    width:500px;
    height:100px;
    position:absolute;
    z-index: 9999;
}