i have a menu with the following markup (stripped back for demo purposes):
HTML Code:
<ul class="megamenu"><!-- BEGIN MENU -->
            <li class="menuitem_fullwidth"><a href="#_" class="menuitem_drop active">First link</a><!-- Begin Full Width Item -->

                     <div class="dropdown_fullwidth"><!-- Begin fullwidth container -->

                                 <div>some content in drop down</div>
                  </div><!-- End fullwidth container -->
            </li><!-- End Full Width Item -->

I've tried adding:
HTML Code:
    $(".megamenu li").hover(
         function() { $('div.dropdown_fullwidth').fadeIn("slow");
        function() { $('div.dropdown_fullwidth').fadeOut("slow");
....but it doesn't work.
Is it possible with jquery or css3?

thanks for any help