var colors = ['#E51E26', '#FEA11C', '#00AA53', '#0063B3', '#503195'];
window.addEvent('domready', function() {
  $$('ul.navlist a.toplevelmenuitem').addEvent('mouseover', function(ev) {
    c = colors[Math.ceil(Math.random()*5)-1];
    ev.target.setStyle('border-color', c);
  }).addEvent('mouseleave', function(ev) {
    ev.target.setStyle('border-color', 'transparent');
  });
});