function centra(p) {
  with (document) {
		if (getElementById('capo').offsetTop <= 5){
      getElementById('capo').style.top = "288px";
      getElementById('capo').style.borderTop = "solid #38241a 1px";
      getElementById('capo').style.borderBottom = "solid #38241a 1px";
		}
		if (getElementById('capo').offsetLeft <= 5){
      getElementById('capo').style.left = "500px";
      getElementById('capo').style.borderLeft = "solid #38241a 1px";
      getElementById('capo').style.borderRight = "solid #38241a 1px";
		}
  }
  if (p == "scroll") {
    with (document) {
      if (getElementById('testo_scroll').clientHeight > alt_testo) {
        alt = 0-getElementById("testo_scroll").clientHeight;
        txtlim = getElementById("testo_scroll").clientHeight-alt_testo;
				step_scroll = delta_scroll/txtlim;
        getElementById('freccia_dw').style.display = "block";
        getElementById('barra_scroll').style.display = "block";
        getElementById('testo_scroll').style.height = alt_testo+"px";
      }
    }
  }
  document.getElementById('schermo').style.visibility = "visible";
}

function credits(n) {
	with (document) {
		if (n != 0) getElementById('credits').style.display = "block";
		else getElementById('credits').style.display = "none";
	}
}