title: css3 :contains selector not work
body: <p>I can't understand what I'm doing wrong, but <code>:contains</code> css selector not work for me. Is it excluded from current css3 implementation? I check it in FF, chrome and IE, all of them ignore <code>background: red</code> property.</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
  &lt;head&gt;
  &lt;style&gt;
  .a {
  border: 1px solid black;
  width: 20px;
  height: 30px;
  position: relative;
  }
  
  .a:contains("1") {
  background: red;
  }
  &lt;/style&gt;
  &lt;/head&gt;
  &lt;body&gt;
  &lt;div class="a"&gt;1&lt;/div&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>