Someone or something has modified the view new_items3 which generates the 'New Items' page. For some reason its body style now overrides the website's theme to use Tahoma 10pt font. Yuck, that's almost as vile as Comic Sans.
Does anyone know anything about this?

I barely understood what you just wrote. And, no, I don't know anything about this.
It seems to have gone away now. Perhaps one of my Firefox plugins was just having an episode.