Sadly I personally have to run this site at 150% browser zoom. The 20ish other sites I use regularly has no issues with scalability.
What's the issue though? Well all images in the forum gets fuzzy and user profiles looks wrong.
Would imagine other people with resolutions higher than 1080p running windows at scale 100% has similar issues as well?
The ideal PPI is 109. This is honestly the sweet spot for windows to run 100% scale. Or if higher PPI like 163 from 27" 4k with 150% windows scale.
Text size should ideally scale with windows text size. Opening a .txt file, write some text and make the window of it small, now drag it over on top of d2jsp to compare the text size.
General suggestion:
Make so the forum borders spans all the way from left to right, no black bars, no matter what resolution ones monitors runs at.
Scale everything up 30%, like larger text, icons, avatars. (we do have "Large Fonts" in settings already, but think this should remain available for people who needs even larger text)
Larger signatures would also be a welcome to accommodate the upgraded scalability. By 30% so from 400x150 to 520x200. But this on its own has already been turned down in site suggestions.
Examples
100% aka default browser on 27" 2160p
https://i.imgur.com/cHZctoN.png150% zoom in browser 27" 2160p (Have to use 150% to make the forum border go all the way from left to right, in general I think 125-130% would be better)
https://i.imgur.com/sWVrBe8.jpgBoth examples have the recommend 150% picked in windows scale
Nice my friend, I also use 4K monitor and have the same issue.. I have to use the forum with 200% zoom because it is just too tiny