Luckily most gui toolkits have a way of disabling CSD. For gtk/libadwaita I recommend something like Gradience to generate a theme with corners of your liking.
It's also used a frightening amount for counter-arguments. Which I personally hat, since it just kills the conversation. Well unless it's already in deeply opinionated context such as this.
"You shouldn't eat ice cream with a fork."
"Doch! (I strongly think the previous statement should be true)"
Good looking UI (designs) and good UX is not the same!
Apple is known for doing both relatively good (especially on the first iphone).
However personally I still dislike the Apple UI (the macos dock eats too much screen space, ios close all where?, ios back gesture,... for example) and UX (the system actively tries to prevent me from doing certain things). I mean, in the end, there often are keybindings that do the job, but those are harder to learn the the emacs keybindings imo.
How about 65535 (2^16-1) ?