document.onmouseover=mouseover;
document.onmouseout=mouseoff;
function mouseover() {
 if (nav.contains(window.event.srcElement))
  nav.style.backgroundColor="#999";
 else
  nav.style.backgroundColor="#666";
 if (window.event.srcElement.tagName=="A")
  window.event.srcElement.className="mouseover";
}
function mouseoff() {
 if (window.event.srcElement.id=="nav")
  nav.style.backgroundColor="#666";
 if (window.event.srcElement.tagName=="A")
  window.event.srcElement.className="";
}