help with closest()

help with closest()

I'm trying understand the closest method..I have the following
 
  1. <ul id="one" class="level-1">
        <li class="item-i">I</li>
        <li id="ii" class="item-ii">II
        <ul class="level-2">
          <li class="item-a">A</li>
          <li class="item-b">B
            <ul class="level-3">
    <li class="item-1">1</li>
              <li id="davide" class="item-2">2</li>
              <li class="item-3">3</li>
            </ul>
          </li>
          <li class="item-c">C</li>
        </ul>
      </li>
      <li class="item-iii">III</li>
    </ul>
      $(document).ready(function () {
      var listItemII = document.getElementById('davide');
      $('li.item-3').closest('ul',listItemII)
        .css('background-color', 'green');



           });
        the result is displayed in the image below..I'm a little confused..Since I'm using a context I would think that it would  not color 1,2 and 3 since first UL is outside of context "davide" any ideas?