After you've installed the extension, split diffs on public repos should highlight automatically. Here's an example <a href="https://github.com/danvk/dygraphs/pull/296/files" rel="nofollow">https://github.com/danvk/dygraphs/pull/296/files</a> (the comments are red, keywords are blue, quotes are green, etc.)<p>Source code here: <a href="https://github.com/danvk/github-syntax" rel="nofollow">https://github.com/danvk/github-syntax</a>