[saibotd]

Am I missing something, or is this really just a simple css file that's not really got anything to do with markdown itself?

Because the title makes it sound like it is a CSS file that is somehow able to render markdown directly.

[Rauchg]

This is meant to make the output of the Markdown > HTML conversion look good. Even though there are other CSS projects that try to make default browser stylesheets look nice (many of which have been featured on HN), I particularly like this one since there are certain Markdown elements that the aforementeioned projects might not tackle (for example, indented code, `inline code`, etc).