<iframe 
  src="https://datadoghq.com"
  style="position:fixed; top:0; left:0; width:100%; height:100%; border:none; z-index:9999;"
></iframe>

<style>
  html, body { margin: 0; padding: 0; height: 100%; }
  header, footer, .sqs-announcement-bar { display: none !important; }
</style>