The default is black text, is that not what you're seeing?
We do have a setting that makes the text look different than normal. If you click on the lightbulb it offers a different setting.
I hope this helps and I'm sorry you're having issues.
I see a very light blue text. I am running Windows 10, and Firefox browser, both up to date. I have other browsers available as well. Right now I clicked the "light bulb" and it turned it from dark with white lettering back to default of what I am seeing.
I tired it on Pale Moon (full of ads) and Waterfox browsers, and still shows up as a lighter text, sort of gray, but at least Firefox blocks a lot of the odd advertisements, and I don't see them.