Just wanted to add a little something here. I found it surprising when you mentioned you didn't like dark themes because you're bound to run into something white when browsing the Internet and that's always unpleasant. I've been using dark themes everywhere for a few years now, and recently I ran into this same problem. I found an interesting solution, however.
There's an extension (for Firefox and Chrome, as far as I know) called TamperMonkey that can run simple scripts to change your browsing experience. With this, you can add custom code on a script to change the background on most sites. It doesn't work on all sites, of course, but it really makes things easier on the eyes.
If you want to try it out, add this to your browser, then create a new script, paste this:
Then you just save the script and refresh your browser windows. This will turn the white backgrounds into grey ones. It's still quite easy to read black text and I haven't had any problems with it so far; also, you can change the RGB colors to make it clearer or darker if you want to. It's a bit of a hack, but it's made my browsing way easier on the last few months.