I think this rule is supposed to alias rust.css with it's full path from the main directory, I have moved rust.css to a css/ subfolder hence the change. Now it seems to be broken somehow.

A bit of history:
6bab5c07e43674e5b0184ff4f75e0ae376cda0c9
5487f140cccd5ac7f83c0d8ad886c46ac69f8446
df02ca1df96950175508191ef98c3b7914cbd9d9