@noleli If we could get some WPTs in for this, maybe we could wag the spec by the tail... Implementation has shown that the spec is not as clear as we'd like on this feature.
Safari even goes so far as to support complex selecting in the `:has()` part of the selector, e.g. `:host(:has(.test [slot="other"]))`
https://codepen.io/Westbrook/pen/KKoJNGm
This leaves me wondering why we can't have complex selectors in `::slotted()`. We really need `::slotted(details summary)`, et al. #cssWorkingGroup