Rated 3 out of 5 stars

le Captain Caveman ar Noll. 29, 2008 · buan-nasc

After you uninstall the extension the following prefs remain changed:
nglayout.debug.enable_xbl_forms
nglayout.debug.disable_xul_cache
nglayout.debug.disable_xul_fastload

1 or all of them is causing all websites to look messed up (like plexos also mentioned).

Resetting the prefs (to false) fixes the issues. Also javascript.options.strict stays set to true which might not be desirable.

Don't have time right now to figure out the why, that's up to you to figure out ;)