Mostly I just want websites to have some internally-consistent set of sizes so that I can Ctrl-scroll to set and then Firefox will remember what's the right siz

Mostly I just want websites to have some internally-consistent set of sizes so that I can Ctrl-scroll to set and then Firefox will remember what's the right size for that website and then I don't have to edit that setting again. (I view HN at 90%, for what it's worth.) But if the user has set a preferred default font size, why on earth would you want a website to override it?