Needed a way to embed a Gist in an Instructure Canvas page. Just paste this into when in HTML editing mode and switch out the address with your gist. CSS came from http://www.bymichaellancaster.com/blog/fluid-iframe-and-images-without-javascript-plugins/

embed.html

<p style="position: relative; padding-bottom: 56.25%; padding-top: 30px; height: 0; overflow: hidden;">
  <iframe style="position: absolute; top: 0; height: 100%; width: 100%;" src="https://gist.github.com/RyanNutt/905983e76c20cf3177b7.pibb" width="300" height="150">
  </iframe>
</p>

You can leave the height and width properties - the actual properties, not the part in style - but most rich text editors will add them back in anyway.

At least in Canvas, it looks like the links to the page back at GitHub on the bottom don't work. Clicking them refreshes the main page.

Okay, so this isn't working quite right. The 56.25% bottom padding is assuming that the iframe is 16:9, which is right for most videos. But the gists can be any height.

Thanks @RyanNutt. For anyone else looking how to do this, I've just blogged about how to use Blair Vanderhoof's gist-embed in Canvas.