title: Attribute category not allowed on element li at this point
body: <p>I came across this <a href="http://demo.webcodo.net/switch-products-view-grid-list-jquery-with-filter-and-cookie/" rel="nofollow">Grid/List layout demo</a> from this <a href="http://www.webcodo.net/grid-list-view-with-jquery-category-filter-cookie-support/" rel="nofollow">page</a>, which is pretty neat, but the <a href="http://validator.w3.org/check?uri=http%3A%2F%2Fdemo.webcodo.net%2Fswitch-products-view-grid-list-jquery-with-filter-and-cookie%2F&amp;charset=%28detect+automatically%29&amp;doctype=Inline&amp;group=0" rel="nofollow">validator</a> gives this error for the category filter:</p>
  
  <pre><code>Attribute category not allowed on element li at this point.
  </code></pre>
  
  <p>Here's the filter markup:</p>
  
  <pre><code>&lt;ul&gt;
     &lt;!-- change the "cat-1", "cat-2", "cat-3" with your "Categories ID" --&gt;
       &lt;li class="cat-active" category="prod-cnt"&gt;All&lt;/li&gt;
       &lt;li class="" category="cat-1"&gt;Category 1&lt;/li&gt;
       &lt;li class="" category="cat-2"&gt;Category 2&lt;/li&gt;
       &lt;li class="" category="cat-3"&gt;Category 3&lt;/li&gt;
  &lt;/ul&gt;
  </code></pre>
  
  <p>Is it possible to fix this or use another attribute? Thank you. </p>