The narrative that #CSS was initially designed to be static, and only later became responsive with things like media, supports, container queries, and now if()… is maybe how things turned out?

But MQs were part of the original proposal – including document age queries, & user "relevance" queries.

This wasn't a big pivot in the vision of the language, but a more continuous project of realizing that vision in relation to changing author needs & browser capabilities over time.