The icon used for CSS files seems to be 2px smaller than other file icons (and the folder icon). When viewing a list of files (such as the folder tree or a version control 'Check status' list), this makes the text CSS file names misaligned with other file names. It also makes the CSS file's row in the list not as tall as other rows. This is hard to notice looking at the UI statically, but it jumps out when you smoothly scroll one of these lists.