JSFiddle - React, Tailwind, and code Playground

HTML

<style type="text/css">
    html, body {
        height: 100%;
    }
    #contentiframewrapper, #cblt_content {
        height: 100%;
    }
    #toolbar {
        height: 200px;
        background-color: #CCC;
        text-align: center;
        font-size: 50px;
        vertical-align: middle;
    }
</style>
<table width="100%" height="100%" cellspacing="0" cellpadding="0" border="0">
    <tbody>
        <tr>
            <td valign="top" id="toolbar">Toolbar
            </td>
        </tr>
        <tr>
            <td width="100%" valign="top" height="100%">
                <div align="center" id="contentiframewrapper">
                     <iframe width="100%" frameborder="0" name="cblt_content" id="cblt_content" src="https://c9.io/" border="0"></iframe>
                </div>
           </td>
    </tr>
    </tbody>
</table>