I have an Ebook reader too (but very old, with slow page building, didn't use in years) and it's much different from a regular screen. Also much smaller too. So I can't compare it to that. My monitor is high resolution, has much more dynamic range than a ereader and is much brighter too. And bigger.

I didn't have a computer as a kid (90s) and didn't use DOS or anything, even though i used computers here and there back then. So I don't think its related to that theory of using too much raw terminal. In fact, I do program or play with commandline tools almost every day or a few days apart a little bit (mostly scripting or trying things out for hobby) in the terminal and I use dark color schemes since years. For programming it is much better to me. But I am very selective until I find a "usable" color scheme. My favorite so far is Gruvbox theme https://github.com/morhetz/gruvbox, but I use something different at the moment. In fact I have set beehaw.org site to dark theme too:

But pure white on black on a monitor just hurts my eyes, when there is lot of text to read.

Firefox has a reader view mode, which I can enable by clicking an icon in the address bar. But for some reason, this icon will not appear for this website here. I even have enabled a setting in the about:config that this icon should be shown for all pages, but it will not for this site.

I used darkreader in the past. But I could not find a solution to just enable temporarily for the current page I am reading. I don't want to enable for all pages. But you actually reminded me of another plugin I totally forgot: Tranquility Reader https://addons.mozilla.org/en-US/firefox/addon/tranquility-1/ and it does exactly what I want and works for this page too. A click will turn it into a readable text temporarily (default black on white, but changeable). So I guess this is a solved problem for me now? Thanks to you, because otherwise I would not remember and lookup again.