title: CSS3 pseudo class not first and last child
body: <p>I have some following HTML code:</p>
  
  <pre><code>&lt;ul&gt;
      &lt;li&gt;number 1&lt;/li&gt;
      &lt;li&gt;number 2&lt;/li&gt;
      &lt;li&gt;number 3&lt;/li&gt;
      &lt;li&gt;number 4&lt;/li&gt;
      &lt;li&gt;number 5&lt;/li&gt;
      &lt;li&gt;number 6&lt;/li&gt;
      &lt;li&gt;number 7&lt;/li&gt;
      &lt;li&gt;number 8&lt;/li&gt;
      &lt;li&gt;number 9&lt;/li&gt;
      &lt;li&gt;number 10&lt;/li&gt;
  &lt;/ul&gt;
  </code></pre>
  
  <p>How can I use CSS3 pseudo-classes to make any <code>li</code> element which is not the first or last have a <code>background-color</code> of <code>tomato</code> for example? It seems that I could use the <code>:not</code> selector.</p>