/*
    When a subnavigation link is moused-over, apply a classname to the parent LI element
    that class definition adjusts the z-index of the LI
*/
function rifSubnav() 
{
    var subnavElements = $$('#sub_navigation li a');
    subnavElements.each( function(navButton){
        navButton.onmouseover = function(){
            Element.addClassName(navButton.parentNode, 'pop');
        };
        navButton.onmouseout = function(){
            Element.removeClassName(navButton.parentNode, 'pop');
        };
    });
}
/* why is this not working? */
// Event.observe(window, 'load', rifSubnav);
rifSubnav();