title: Is -webkit-focus-ring-color a CSS variable?
body: <p>Browsing through default Webkit CSS <a href="http://codesearch.google.com/codesearch#OAMlx_jo-ck/src/third_party/WebKit/Source/WebCore/css/html.css" rel="nofollow">here</a> I noticed the following piece of code:</p>
  
  <pre><code>:focus {
      outline: auto 5px -webkit-focus-ring-color
  }
  </code></pre>
  
  <p>It seems <code>-webkit-focus-ring-color</code> is a variable of some sort. I thought CSS could <em>not</em> have variables. What is going on here?</p>