Talking about PIXL.US’ site I think a vector logo would be better. The actual PNG looks very blurred.
Moreover, to appreciate the uploaded photos against a neutral background it would be useful to have a neutral background also in the dark theme of the site.
The forum site logo and text is all one image. Its only slightly blurry if you’re on mobile or a small screen. On the desktop is looks fine to me.
The default theme is white and white is neutral.
The dark theme is a slightly warm gray, but if you click the image you get a light box that is closer to black.
We don’t stray from the upstream discourse package too much, because we are the same as you: our free time is spent doing things other than maintaining patch sets.