But it would be better still if browsers offered an opt-in modern default style, to relieve us developers of having to make assumptions about the user's visual needs, which should be the domain of the user agent.
Firefox had that for a long time, hidden in a menu, but discoverable eventually. It also used to have a menu for Alternate Styles when a webpage included named LINKs to alternate styles (allowing pages to have a heavy, preferred default but offer the user other options, without needing to add a "theme picker" in the HTML somewhere).
Outside of dedicated "Reader Views" it seems like we've given up on the idea that might be something the browser should do. (Which, I appreciate the "Reader View" as an easier to discover way to do this, even if I think moving it into a "modal" with its own liminal space continues the narrative of the browser moving away from being a "user agent" to being an "application runtime".)
