A shadow-piercing descendant combinator (>>>) is defined in https://drafts.csswg.org/css-scoping/#deep-combinator as a straightforward replacement for `/deep/` combinator (which was for Shadow DOM V0), with a restriction that it is only allowed for selectors in querySelector() (aka static profile, not in dynamic profile for styling). See spec discussions: https://github.com/w3c/webcomponents/issues/78 (already closed) https://github.com/w3c/csswg-drafts/issues/640