if (document.images) {
    // preload the alternate images offscreen
   homeon = new Image();
   homeon.src = "images/home-on.gif";
   abouton = new Image();
   abouton.src = "images/about-on.gif";
   valueon = new Image();
   valueon.src = "images/value-on.gif";
   searchon = new Image();
   searchon.src = "images/search-on.gif";
   clientson = new Image();
   clientson.src = "images/clients-on.gif";
   candidateson = new Image();
   candidateson.src = "images/candidates-on.gif";
   specializationon = new Image();
   specializationon.src = "images/specialization-on.gif";
   contacton = new Image();
   contacton.src = "images/contact-on.gif";
   homeoff = new Image();
   homeoff.src = "images/home-off.gif";
   aboutoff = new Image();
   aboutoff.src = "images/about-off.gif";
   valueoff = new Image();
   valueoff.src = "images/value-off.gif";
   searchoff = new Image();
   searchoff.src = "images/search-off.gif";
   clientsoff = new Image();
   clientsoff.src = "images/clients-off.gif";
   candidatesoff = new Image();
   candidatesoff.src = "images/candidates-off.gif";
   specializationoff = new Image();
   specializationoff.src = "images/specialization-off.gif";
   contactoff = new Image();
   contactoff.src = "images/contact-off.gif";
}
function imgAct(imgName) {
  if (document.images) {
     document[imgName].src = eval(imgName + "on.src");
 }
}
function imgInact(imgName) {
  if (document.images) {
     document[imgName].src = eval(imgName + "off.src");
 }
}