function rollon() {

  if (window.event.srcElement.className == "LeftNav") {

     window.event.srcElement.className = "LeftNavHighlight";

  }

}

document.onmouseover = rollon;

function rolloff() {

  if (window.event.srcElement.className == "LeftNavHighlight") {

     window.event.srcElement.className = "LeftNav";

  }

}

document.onmouseout = rolloff;