We're finally getting a  element we can fully control with CSS! A bunch of other stuff needed to be added to the platform to make it work, and the good news is we can use it a lot of them independently of . Resources: Chrome's article on the new , and how you can provide feedback. The CSS appearance property. Nope, I still don't know what it does. The Popover API. "On popover accessibility: what the browser does and doesn’t do" by Hidde de Vries and Scott O'Hara. The CSS anchor positioning API. The previous spatnav spec effort. The hidden attribute until-found value (sorry, I said if-found in the episode). The CSS element function. Timing of cloning for the  element. Animating to height auto. The new entry-exit animation feautres. The proposed command and commandfor attributes which give buttons declaritive activation behavior.