Comment by CamperBob2

There's no Preferences button. If there is, they've either hidden it well, or it's not visible without a login.

There should simply be a button -- a conspicuous one -- that toggles the color scheme. It's trivial to add such a button. It doesn't need to be tied to a user ID; it doesn't even need to set a cookie. The fact that no such button exists is a choice someone made, a poor choice that disregards decades of human-machine interface research.

Failure to go full Karen about goofy things like this has made the Web a little worse for almost everyone in one way or another. So... there ya go.