KDE definitely still lets you theme like crazy, I believe including the scroll bar settings

The CSS comment sounds like Gnome. I used Gnome for fifteen years and got tired of what you're complaining about and switched to KDE eight or nine months ago and haven't looked back

Actually a few years ago KDE plasma had a huge volume icon appearning in the middle of the screen everytime you changed the volume (which I do subconsciously all the time as it's just a simple scrollwheel flick in the bottom right of the screen), which looked horrible and was right in the middle of that what I'm working on or watching.

The only way to disable that was to edit a javascript file of KDE, which, indeed, did get overwritten back to the default one whenever doing a system update.

So I use KDE sometimes. Never as much as when it was KDE 3.5 though. KDE 4 and higher made me lose interest in it and stuff like the above is part of that. Also the fact that there are some textual config files in recent KDE versions, which have base64 encoded parameters in them (rather than human readable/editable strings), and these base64 encoded parameters are actually UTF-16 strings. With all due respect, but no.

That's one thing I really like about KDE - endless customizability. I actually end up using a lot of the defaults anyways.

KDE can be completely transformed by themes and they've also just introduced a choice of accent color for the default Breeze theme. A bit similar to what macOS has.

I really love that about KDE, the configurability.