It has been made for Google Chrome, but it seems to work quite well in Firefox (better than I had expected).

Aside from increasing the font size and making posts etc. bigger to fit the bigger text in, it also removes (some, or all?) advertisement. I don't think anyone has a problem with that ;)

The default CSS of Facebook is horrible to work with. For example, it often uses !important and per element styles which is considered very bad practice. For this reason, it's quite hard to write it well. The Google+ version that I haven't published is much shorter.

This userstyle tries to leave the current design alone as much as possible.