Contao 3, MooTools and menu

Hi,

I've created at css based menu that works like a charm. But when I enable MooTools it stops working. Nothing happens when hovering the menu. The problem is when hovering style="opacity: 0; visibility: hidden;" doesn't change.

Here's the HTML:

Code:

---

<nav class="mod_navigation block" id="mainmenu">
Skip navigation
<ul class="level_1">
<li class="submenu leftcol sibling first">About us
<ul class="level_2" style="opacity: 0; visibility: hidden;">
<li class="leftcol first">Who We Are
<li class="leftcol last">Management Team[/list]
[/list]
<a id="skipNavigation2" class="invisible"></a>
</nav>

---

I've tried disabling all css, but there's no change in behavior.

What am I missing here? :?


Michael