grishka
The ability to choose the tint color of an instance's UI with a color picker in the admin panel
The way it works right now, it's impossible to fully change the UI colors at runtime. Even if I switched from PostCSS variables to native CSS ones, that would not help with recoloring the SVG icons I embed into my CSS files (also done by PostCSS at compile time).
I'm open to suggestions how to make this possible though. But I do want to keep the icons embedded in CSS to avoid loading extra files (by putting them into a sprite sheet or something) or complicating page rendering (by directly using <svg> in HTML).
Hot recoloring (i.e. previewing the page without reloading it during picking a new color) would indeed be difficult to implement, so maybe we shouldn't.
However, once the new color setting is saved, the server can just serve CSS files with new color settings. Or something like that, I'm actually very far from frontend development.
Custom CSS is kind of a superset of this and you successfully used it to make your server's UI blue, so I'm considering this feature request satisfied
There are some images remaining that cannot be customized in a custom CSS though, for example, lnkouter.svg. But I think I'll contribute the fix myself some time soon.