You'll perhaps take this as snark, but I am not going to read light gray text on a white background with a poorly rendered font (windows 7, firefox 27, 47yo eyes).
FWIW, I've had good luck with using the "select all" keyboard shortcut in those circumstances. I believe that you have an additional advantage in that Firefox has an option(1) to deactivate their stylesheets (one at a time, IIRC) which can also get you back into normal styling without a great deal of effort.
1= or it used to but without it in front of me I can't promise it still does