Internally we use a [[https://pypi.python.org/pypi/pygments-style-github | github]] based style which people like because it looks good and because github. pygmentize also has bunch of other built in styles which you can list with `pygmentize -L styles`. Some of them are minor variations while others would clash badly (dark background).
I looked into adding this to PhutilPygmentsSyntaxHighlighter but ran into trouble since the css style definitions look like they are tied into the rest of remarkup-land. For comparison cgit just dumps a big old `<style>` block http://git.zx2c4.com/cgit/tree/filters/syntax-highlighting.py?id=v0.10.2 Was not sure how to structure it here since passing along css isn't part of the contract for PhutilSyntaxHighlighterEngine.