var _ua = navigator.userAgent.toLowerCase();
var _iphone = /iphone|ipod/i.test(_ua);
var _android = /android/.test(_ua);
var _ipad = /ipad/.test(_ua);
var _tablet = _ipad;
if(!_tablet && _android){
	_tablet = !(/mobile/.test(_ua));
}

if(_tablet){	
	//tablet
	document.write('<link rel="stylesheet" media="screen and (orientation:portrait)" href="css/tablet_portrait.css">');
}else{
	//smartphone
	document.write('<link rel="stylesheet" media="screen and (max-width: 600px)" href="css/small.css" />');
	document.write('<link rel="stylesheet" media="screen and (max-width: 600px) and (orientation:landscape)" href="css/landscape.css">');
}