title: preg_replace_callback(): Requires argument 2
body: <p>I'm not quite sure what to do here.  Any help from someone smarter than I would be greatly appreciated...</p>
  
  <pre><code>Warning: preg_replace_callback(): Requires argument 2, 'strtolower(':0')', to be a valid callback in ....\ on line 380.
  
  $css = preg_replace_callback('/(text-shadow\:0)(;|\})/ie', "strtolower('$1 0 0$2')", $css);
  </code></pre>