Unreadable colours for Documentation

[Onanymous]

That is very smart way to say that it simply sucks. If you (of course not you personally) don't use system theme and use css instead - allow user to subsitute his own css on the fly.

Having said that you can change the stylesheet of your whole application using qss

assistant -stylesheet=fullpath/ass.qss

and simplest ass.qss would contain
QTextEdit{ background-color: white; }

That of course will make background white, so it is only a quick and dirty half-solution. I am lazy to look for how to change text color at the moment, but would not mind knowing that myself.