title: My nav is undefined, even with my document type declared
body: <p><a href="http://jsfiddle.net/cEv2S/" rel="nofollow">http://jsfiddle.net/cEv2S/</a> - My index page, fails to validate via xhtml 1.1 standards</p>
  
  <p>I receive the validation error " Line 38, Column 6: element "nav" undefined "</p>
  
  <pre><code>&lt;div id="header"&gt;Leon's CS150 Assignment&lt;/div&gt;
      &lt;nav&gt;   &lt;!-- this is the line quoted in my error message --&gt;
          &lt;div&gt;
              &lt;a class="Menu-Item" href="#"&gt;Home&lt;/a&gt;
              &lt;a class="Menu-Item" href="about.html"&gt;About&lt;/a&gt;
              &lt;a class="Menu-Item" href="cv.html"&gt;CV&lt;/a&gt;
              &lt;a class="Menu-Item" href="../wordpress"&gt;Wordpress&lt;/a&gt;
              &lt;a class="Menu-Item" href="../webshop/catalog"&gt;Webshop&lt;/a&gt;
          &lt;/div&gt;
      &lt;/nav&gt;
  </code></pre>
  
  <p>My nav is clearly defined in my CSS and has been fine until I tried to validate, does anybody know why this is happening? I've even declared the document type.</p>
  
  <p>Thanks in advance.</p>