I was debugging this site using the Chrome “Inspect Element” option (which is just amazing), and noticed the huge amount of whitespace that was in the HTML generated by Jekyll. Going by this bug report the engine is not smart enough to exclude whitespace between lines of code. I have seen extensions that claim to be able to solve this, but as I’m hosting on GitHub I need to keep to the standard install setup. I had a thought of how to solve this, and it works surprisingly well!
An updated solution is available.