yes, mixins. even just static sets of declarations would be a great start, e.g., wanting to apply the same set of base rules to both an entity and various class

yes, mixins. even just static sets of declarations would be a great start, e.g., wanting to apply the same set of base rules to both an entity and various classes without error-prone repetition (which you typically separate to have control over cascading and specificity). css variables in media queries would be helpful too, but mixins to me is the next big step after :has() (oh so useful, come on firefox!) and this nested css syntax. unfortunately, it may be years for us to see it in browsers. there's no consensus yet on mixin syntax or where in the css lifecycle it would be implemented (there are potentially serious performance implications apparently).