Personally, I don't tweak Mac OS X.
There used to be an application called Kameleon
which might do the job.
You might want to check out TinkerTool
, which provides a number of tweaks and hidden features to the OS X.
I never tried any of those myself, so you will have to explore them yourself.
I would simply put the monitor a bit closer if I were you.
UserAgent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:126.96.36.199) Gecko/20110420 AlexaToolbar/alxf-2.11 Firefox/3.6.17