function act(id) {
  if (document.getElementById)
  {
        document.getElementById('uno').style.backgroundPosition = "0px -93px";
        document.getElementById('due').style.backgroundPosition = "0px -93px";
        document.getElementById('tre').style.backgroundPosition = "0px -93px";
        document.getElementById('quattro').style.backgroundPosition = "0px -93px";
        document.getElementById('cinque').style.backgroundPosition = "0px -93px";
        document.getElementById('sei').style.backgroundPosition = "0px -93px";
        document.getElementById(id).style.backgroundPosition = "0px 0px ";
        switch (id) {
        
          case 'uno': document.getElementById('scritta').style.backgroundPosition = "0px -45px "; break;
          case 'due': document.getElementById('scritta').style.backgroundPosition = "0px -90px";break;
          case 'tre': document.getElementById('scritta').style.backgroundPosition = "0px -135px";break;
          case 'quattro': document.getElementById('scritta').style.backgroundPosition = "0px -180px";break;
          case 'cinque': document.getElementById('scritta').style.backgroundPosition = "0px -225px";break;
          case 'sei': document.getElementById('scritta').style.backgroundPosition = "0px -270px";break;
        }
  }
}

function inact() {
  if (document.images)
  {
        document.getElementById('uno').style.backgroundPosition = "0px 0px ";
        document.getElementById('due').style.backgroundPosition = "0px 0px ";
        document.getElementById('tre').style.backgroundPosition = "0px 0px ";
        document.getElementById('quattro').style.backgroundPosition = "0px 0px ";
        document.getElementById('cinque').style.backgroundPosition = "0px 0px ";
        document.getElementById('sei').style.backgroundPosition = "0px 0px ";
        document.getElementById('scritta').style.backgroundPosition = "0px 0px ";
  }
}