function mouseOver(a)
{
  switch (a)
  {
   case 1:
    document.button1.src ="/images/buttonhomelight.gif";
    break;
   case 2:
    document.button2.src ="/images/buttonwerkwijzelight.gif";
    break;
   case 3:
    document.button3.src ="/images/buttontarievenlight.gif";
    break;
   case 4:
    document.button4.src ="/images/buttonartikelenlight.gif";
    break;
   case 5:
    document.button5.src ="/images/buttonroutelight.gif";
    break;
   case 6:
    document.button6.src ="/images/buttoncontactlight.gif";
    break;
  }
}

function mouseOut(a)
{
  switch (a)
  {
   case 1:
    document.button1.src ="/images/buttonhome.gif";
    break;
   case 2:
    document.button2.src ="/images/buttonwerkwijze.gif";
    break;
   case 3:
    document.button3.src ="/images/buttontarieven.gif";
    break;
   case 4:
    document.button4.src ="/images/buttonartikelen.gif";
    break;
   case 5:
    document.button5.src ="/images/buttonroute.gif";
    break;
   case 6:
    document.button6.src ="/images/buttoncontact.gif";
    break;
  }
}