function setActiveStyleSheet(title,flag){ 
		  
		  var i, a, main;
		  for(i=0; (a = document.getElementsByTagName("link")[i]); i++)
		  {
			if(a.getAttribute("rel").indexOf("style") != -1 && a.getAttribute("title"))
			{
			  a.disabled = true;
			  if(a.getAttribute("title") == title) a.disabled = false;
			}
		  }
		  if(flag){ 
			  switch (title){
				  case "style1" : 
						document.getElementById("t1").className='on';	
						document.getElementById("t2").className='';
						document.getElementById("t3").className='';
						document.getElementById("t4").className='';
						break;
				 case "style2" : 
						document.getElementById("t1").className='';
						document.getElementById("t2").className='on';
						document.getElementById("t3").className='';
						document.getElementById("t4").className=''; 
						break;
				  case "style3" : 
						document.getElementById("t1").className='';
						document.getElementById("t2").className='';
						document.getElementById("t3").className='on';
						document.getElementById("t4").className='';
						break;
				  case "style4" : 
						document.getElementById("t1").className='';
						document.getElementById("t2").className='';
						document.getElementById("t3").className='';
						document.getElementById("t4").className='on';
						break;
			  }
			  
			//function lấy tu trang suplier()
			//alert(flag);
			setStyle(title) ; 
		  }
	}
	function getActiveStyleSheet(){
	  var i, a;
	  for(i=0; (a = document.getElementsByTagName("link")[i]); i++) { 
		if(a.getAttribute("rel").indexOf("stylesheet") != -1 && a.getAttribute("title") && !a.disabled) 
		{
			return a.getAttribute("title");
		}
	  }
	  return null;
	}
	function getPreferredStyleSheet() {
	  var i, a ;
	  for(i=0; (a = document.getElementsByTagName("link")[i]); i++) {
		if(a.getAttribute("rel").indexOf("stylesheet") != -1 && a.getAttribute("rel").indexOf("alt") == -1 && a.getAttribute("title") ) 
		{
			return a.getAttribute("title");
		}
	  }
	  return null;
	}
	function createCookie(name,value,days) {
	  if (days) {
		var date = new Date();
		date.setTime(date.getTime()+(days*24*60*60*1000));
		var expires = "; expires="+date.toGMTString();
	  }
	  else expires = "";
	  document.cookie = name+"="+value+expires+"; path=/"; 
	}
	function readCookie(name) {
	  var nameEQ = name + "="; 
	  var ca = document.cookie.split(';');
	  for(var i=0;i < ca.length;i++) {
		var c = ca[i];
		while (c.charAt(0)==' ') c = c.substring(1,c.length);
		if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
	  }
	  return null;
	}
	
	window.onload = function(e) { 
	  var cookie = readCookie("style");	
	  if(cookie){	  
	  	setActiveStyleSheet(title,true);
	  }else{
		  setActiveStyleSheet('style1',true);
		}
	} 
	var cookie = readCookie("style");
	var title = cookie ? cookie : getPreferredStyleSheet(); 
	setActiveStyleSheet(title,false);