Script is not working in div with fixed position in Safari and iCab

Script is not working in div with fixed position in Safari and iCab

This script does not work properly when the div #nav has position fixed. The error occurs only in Safari and iCab and only with #nav position fixed. In Firefox, IE, Opera an in Mac OS Chrome it works fine.

Has anyone any idea what the problem is?

   
    
    
  1.  $("#nav ul li ul").hide(); if ($("#nav ul li ul li").hasClass("aktuell")) { $(".aktuell").closest("ul").show("fast", navKl); } $("#nav ul li h3").click(function() { if ($(this).next().is(":hidden")) { $("#nav ul li ul").slideUp("normal", navKl); } $(this).next().slideToggle("normal", navKl); }); function navKl() { if ($(this).is(":visible")) { $(this).parent().addClass("offen"); } else { $(this).parent().removeClass("offen"); } };
    2.