.parents() is the selector which you need to use instead of find.
find selector will try to find the element which is child of current selector. But I think #main-wrapper must be the parent of your content.
<ul class="level-1">
<li class="item-i">I</li>
<li 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 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>
If we begin at item A, we can find its ancestors:
$('li.item-a').parents().css('background-color', 'red');
The result of this call is a red background for the level-2 list, item II, and the level-1 list (and on up the DOM tree all the way to the element).
See some more examples here