IMO, the default Lemmy style is ridiculous on desktop (especially widescreen). I saw a few posts on other servers with some Stylus CSS changes and they were a good start. I made a few changes to get rid of some of the crazy font sizes, padding/margin, and width.
The CSS: https://pastebin.com/b71sNaRe
Stylus Chrome extenstion: https://chrome.google.com/webstore/detail/stylus/clngdbkpkpeebahjckkjfobafhncgmne
Screenshots: https://i.imgur.com/UdKigJD.png https://i.imgur.com/PBNb1SK.png
Hopefully this makes things more bearable for a few people. (If you use dark mode, just delete lines 10, 11, and 12.)
This is great. I've already started tweaking it. I don't know why the default font color here is a dark gray instead of black it really hurts readability. In fact, some of the other color choices are just not very nice.