function chgFbtn(btn){
	var manager = new CookieManager({shelfLife:30});
	var openItem = manager.getCookie('font_size');

	if(btn == '0'){
		if(openItem != null){
			btn = openItem;
		}	else {
			btn = 'm';
		}
	}
	window.document.getElementById('f_l_n').style.display = "block";
	window.document.getElementById('f_l_h').style.display = "none";
	window.document.getElementById('f_m_n').style.display = "block";
	window.document.getElementById('f_m_h').style.display = "none";
	window.document.getElementById('f_s_n').style.display = "block";
	window.document.getElementById('f_s_h').style.display = "none";
	window.document.getElementById('f_' + btn + "_n").style.display = "none";
	window.document.getElementById('f_' + btn + "_h").style.display = "block";

	if(btn == 'l'){
	size = '120%';
	} else if (btn == 'm'){
	size = '100%';	
	} else {
	size = '90%';	
	}
//	window.document.getElementById('test').style.fontSize = size;	
	window.document.body.style.fontSize = size;	
	manager.setCookie('font_size', btn);
}