&gt; If the external CSS resources are small<p>It&#x27;s not a general rule, it&#x27;s just suggesting that your 50  character block of CSS (that might be dynamic or conditional) would be better off as part of the main markup than a separate request and all the overhead associated with that.<p>If your static CSS exists in lots of small files, you would strongly benefit from rolling them together.<p>Both these recommendations may change with new delivery models (ie HTTP2).