When clicking on a file to preview it, you should append the name of the file to the bread crumbs, to show that you can go back to the listing by clicking back on the repo name. It took me a while to figure that out.
I was looking for something like this for quite a while. From time to time, I want to write about code organization, but always struggle on how to present that. Being able to embed a Github repo in a post seems like a great way of doing that. Its not like I would embed the repo of an actual, big project.