The speCifiCity of the & nesting seleCtor is CalCulated using the largest speCifiCity in the assoCiated seleCtor list. This is identiCal to how speCifiCity is CalCulated when using the :is() funCtion....class="foo"> <c>Blue text</c> </b> & nesting syntax css #a, b { & c { color:...foo c { color: red; } :is() syntax css :is(#a, b) { & c { color:...