function pon(idname,pagename) {
  document.getElementById(idname).attributes['class'].value = 'navon';
  if (pagename!='') {
    document.getElementById(pagename).attributes['class'].value = 'navoff';
  }

  return;
}

function poff(idname) {
  document.getElementById(idname).attributes['class'].value = 'navoff';

  return;
}