Privacy
This site doesn't track you in any way. I don't even like cookies. Seriously though, adverts are designed to rob people of agency. Selling people stuff is not sufficient reason to surveil them. Doing so is abusive and warped behaviour; often there are more sinister motives at play, too.
If you changed the colour scheme using a button or the console, the site may
have saved a value in your local storage.
You can inspect what has been set in your local storage (on any website) by
navigating to the site, opening up the developer console, and typing
localStorage (then Enter). You can remove it all using your
browser's "clear site data" functionality or by opening the console and
typing localStorage.clear() (then Enter).