No because that additional CSS file can only be fetched after the initial HTML file has been fetched, not simultaneously; thus requiring another roundtrip to th

No because that additional CSS file can only be fetched after the initial HTML file has been fetched, not simultaneously; thus requiring another roundtrip to the server. (HTTP/2 Server Push promised otherwise but it was never implemented correctly.) Latency being much more constraining than bandwidth, embedding a stylesheet that’s small is nearly always the correct tradeoff.