Re colors, I've found an answer reasonably satisfactory for me. Compton. From what I've done with it so far, it doesn't appear to be flexible about the details of the color change, but it will invert all the colors of the whole window easily & that is a big improvement for me. A bonus is that it can be used for ANY window running ANYTHING. Cool!!!!!
https://askubuntu.com/questions/1346...for-one-window
Font size in the text wIndow (I should have said this earlier) isn't a problem because it can be zoomed.
What remains is figuring out how to get the font size in the ui menus large enough to read.
[ edited out a mistake here ]