function startList() {
  var aNav = document.getElementsByTagName('ul');
  for (var iNav = 0; iNav < aNav.length; iNav++) {
    if (aNav[iNav].className != 'nav') {
      continue;
    }
    for (var i = 0; i < aNav[iNav].childNodes.length; i++) {
      var node = aNav[iNav].childNodes[i];
      if (node.nodeName.toLowerCase() == 'li') {
        node.onmouseover = function() {
          this.className += ' over';
        };
        node.onmouseout = function() {
          this.className = this.className.replace(' over', '');
        };
      }
    }
  }
}
window.onload=startList;