I used to loathe websites with light text on black backgrounds. It's terribly painful to look at. Dark text on light backgrounds is much better. But then, I talked to other people and learned that not all eyes work the way my eyes work. That things that are painful for me to look at, aren't painful for everyone to look at. And things that aren't painful for me to look, are actually painful for some other people.
So to get around this, some apps and social medias and websites and other things tend to have a Day Mode and a Night Mode. Dark text on light backgrounds and light text on dark backgrounds. Offering choice since one size cannot fit all.
Do RPG rulebooks need to come in pairs? A Day Mode PDF and a Night Mode PDF? Is that something that could make texts more readable?