title: Syntax documentation for a dollar sign in CSS?
body: <p>I came across some HTML recently that denoted a style this way:</p>
  
  <pre><code>&lt;style type="text/css"&gt;
       ${demo.css}
  &lt;/style&gt;
  </code></pre>
  
  <p>Obviously, this is including the "demo.css" file. But I've never seen CSS written this way. I've only seen the @import syntax for including files. </p>
  
  <p>A cursory search around Google turned up nothing. Is this syntax documented anywhere? Is this some sort of templating thing? </p>