var d = window.document;
if(navigator.userAgent.indexOf('iPhone') > -1)
	d.write('<meta name="viewport" content="width=device-width, maximum-scale=2.0, minimum-scale=0.5,user-scalable=yes,initial-scale=1.0" />');
else if(navigator.userAgent.indexOf('Android') > -1)
	d.write('<meta name="viewport" content="width=device-width, maximum-scale=2.0, minimum-scale=0.31,user-scalable=yes,initial-scale=1.0" />');
else if(navigator.userAgent.indexOf('iPad') > -1)
	d.write('<meta name="viewport" content="width=1024" />');