var tab = {
peek:0,
init: function(start){
var tabs = this.setup.tabs;
var pages = this.setup.pages;


for(var i=0; i<pages.length; i++) {
if(i !== 0) pages[i].style.display = 'none';
tabs[i].onclick = function(){ tab.showpage(this); return false; };
}
this.peek = start;
this.showpage(tabs[this.peek]);
},

showpage: function(obj){
var tabs = this.setup.tabs;
var pages = this.setup.pages;
var num;

for(num=0; num<tabs.length; num++) {
if(tabs[num] === obj) {
tab.peek = num;
break;
}
}

for(var i=0; i<pages.length; i++) {
if(i == num) {
pages[num].style.display = 'block';
tabs[num].className = 'select';
}
else{
pages[i].style.display = 'none';
tabs[i].className = null;
}
}
}
}

window.onload=function(){

tab.setup = {
tabs: document.getElementById('tab').getElementsByTagName('li'),

pages: [
document.getElementById('step1'),
document.getElementById('step2'),
document.getElementById('step3'),
document.getElementById('step4')
]
}

tab.init(0);
}

function proceed(num){
if(tab.peek + num < tab.setup.tabs.length && 0 <= tab.peek + num){

tab.showpage(tab.setup.tabs[tab.peek + num]);
}
}
function error_none(){
  return true;
}
onerror = error_none;