// toggle visibility 
function toggle()
{
   target1 = document.getElementById('computer_drivers_content');
   target2 = document.getElementById('computer_drivers_teaser');
   if(target1.style.display == "none")
   {
      target1.style.display = "";
      target2.style.display = "none";
   } 
   else
   {
      target1.style.display = "none";
      target2.style.display = "";
   }
}