<!doctype html>
<html>
  <head>
    <meta charset="utf-8" />
    <style>
html, body { height: 100%; }
#outside { display: block; height: 15%; width: 100%; }
#embed { height: 70%; width: 100%; }
    </style>
  </head>
  <body>
    <h3>Embed Grist</h3>
    <textarea id='outside'></textarea>
    <iframe id='embed' src=""></iframe>
  </body>
</html>