It's nice, but it's not quite ready for use yet.<p>It's not supported on the previous main version of Safari, so everyone following the "last two major versions" of browser support rule can't use them.<p>Also, it's currently limited to only dialogs and popovers (and custom events, but in those cases you need js anyway).<p>It'll be more useful once it can control:<p>- details (open, close, toggle)<p>- video (play, pause, toggle play state, set seek point, mute, set volume)<p>- select (open/close widget, set/unset value(s))<p>- input (open/close widget, set/unset value(s))<p>- all elements (add/remove/toggle/set a class/attribute)