var activeID="1"

function opacity(id, opacStart, opacEnd, millisec) {
	//speed for each frame
	var speed = Math.round(millisec / 100);
	var timer = 0;
	var numer=id;
	id="div"+id

	//determine the direction for the blending, if start and end are the same nothing happens
	if(opacStart > opacEnd) {
		for(i = opacStart; i >= opacEnd; i--) {
			setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
			timer++;

		if(i==opacEnd) document.getElementById(id).style.display="none";
		}
	} else if(opacStart < opacEnd) {
		for(i = opacStart; i <= opacEnd; i++)
			{
			if(i==opacStart) document.getElementById(id).style.display="block";
			setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
			timer++;
			if(i==opacEnd) activeID=numer;
		}
	}
}

//change the opacity for different browsers
function changeOpac(opacity, id) {
	var object = document.getElementById(id).style; 
	object.opacity = (opacity / 100);
	object.MozOpacity = (opacity / 100);
	object.KhtmlOpacity = (opacity / 100);
	object.filter = "alpha(opacity=" + opacity + ")";
}

function Pokaz(id){

//ukrywamy id aktywne
opacity(activeID, 100, 0, 1000) 
document.getElementById("pn"+activeID).className="";

//pokaz id
opacity(id, 0, 100, 1000) 
document.getElementById("pn"+id).className="activ";

location.href='#top'
}



function start(){

//ukrywamy divy (oprocz 1)
var i=0;
for (i=2;i<=5;i++) document.getElementById("div"+i).style.display="none";

//ustawiam opacity na 0
for (i=2;i<=5;i++) changeOpac(0, 'div'+i);

}

window.onload = function(event){
  start();
}