We are much farther along with the development of (and experimentation with) size-based container queries. I want to make sure we have a plan from the start for how additional container/query types (like style queries) will be handled in the top-level syntax, but we could move the internal details of style-based queries into level 4, if it helps browsers more quickly get interop on the more established size features.
/cc @jensimmons who suggested this approach.