if(document.images) {

  
  home_on = new Image;
  home_on.src = 'img/home_on.gif';
  home_off = new Image;
  home_off.src = 'img/home_off.gif';
  
  buero_on = new Image;
  buero_on.src = 'img/buero_on.gif';
  buero_off = new Image;
  buero_off.src = 'img/buero_off.gif';
  
  
  loesungen_on = new Image;
  loesungen_on.src = 'img/loesungen_on.gif';
  loesungen_off = new Image;
  loesungen_off.src = 'img/loesungen_off.gif';
  
  referenzen_on = new Image;
  referenzen_on.src = 'img/referenzen_on.gif';
  referenzen_off = new Image;
  referenzen_off.src = 'img/referenzen_off.gif';
  
  
  kontakt_on = new Image;
  kontakt_on.src = 'img/kontakt_on.gif';
  kontakt_off = new Image;
  kontakt_off.src = 'img/kontakt_off.gif';

}

function imgAct(img_name)
{
  if(document.images) {
    img_on = eval(img_name + '_on.src');      
	  document.getElementById(img_name).src = img_on;
  }
}

function imgInact(img_name)
{
  if(document.images) {
    img_off = eval(img_name + '_off.src');          
    document.getElementById(img_name).src = img_off;
  }
}