It is great to have codepen, but our community prefers jsfiddle as most of the examples and issues are tested there. jsfiddle does have embed code, and this is what http://jsfiddle.net/hw9rcLL8/ looks like in iframely.
Here is what the embed code looks like:
<iframe width="100%" height="300" src="//jsfiddle.net/hw9rcLL8/embedded/" allowfullscreen="allowfullscreen" frameborder="0"></iframe>
What would be the way forward to support this on our discourse?