Same here. As far as I was able to discern with some research, it has to do with the rendering engine that Chrome uses - I think GDI+ instead of DirectDraw, or perhaps vice-versa, whereas Firefox and IE use the better one, and IIRC Safari has its own.

EDIT: This page has more info, but I'm not sure if it's up-to-date: http://www.smashingmagazine.com/2012/04/24/a-closer-look-at-...