In the words of the late John F. Kennedy: "We choose to do things not because they are useful, but because they are excuses to vibecode another Codeforces extension". People were confused when he said this because they didn't know what "Codeforces" meant. The Soviets interpreted it as a subtle threat about American capabilities in the yet uncharted field of cyberwarfare. But I digress.

There's no need to make 998244353 extensions to do things that you can do with existing options (or better yet, vanilla site functionality).

• If you want dark mode, use dark reader. You also get dark mode on other websites.

• If you want simple analytics about your profile, use CF Analytics.

• If you want estimated rating changes, use carrot.

• For anything else, it's probably already possible in the vanilla site.