var gapBeforeFooter = 5;
var menuItemWidth = 171;

Event.observe(window, 'load', function(e) {
    $$('ul#nav>li').each(function(e) {
        e.observe('mouseover', function(e) {
            var submenu = this.down("ul");
            var submenuOffset = submenu.cumulativeOffset();
            var bottom = submenu.getHeight() + submenuOffset.top;
            var footer = $('Footer');
            var footerOffset = footer.cumulativeOffset();

            if (bottom > footerOffset.top) {
                var diff = footerOffset.top - bottom - gapBeforeFooter;
                //alert(submenuOffset.top - diff);
                submenu.setStyle({ top: diff + 'px', left: menuItemWidth + 'px', borderLeftStyle: 'solid', borderLeftWidth: '3px', borderLeftColor: '#ffffff' });
            }
        });
    });
    $('nav')
        .select('li')
        .invoke('observe', 'mouseover',
            function(e) {
                this.addClassName('over');
            })
        .invoke('observe', 'mouseout',
            function(e) {
                this.removeClassName('over');
            });
});