<!DOCTYPE html>  
<html lang="en">  
<head>  
<meta charset="utf-8" />  
<title>Screen Width Test-www.jb200.com</title>  
<style type="text/css">  
@media all and (max-device-width: 1024px) {  
body {  
  background-color: yellow;  
}  
}
</style>
</head>  
<body>  
<script type="text/
javascript">  
var agent = navigator.userAgent.toLowerCase();  
var scrWidth = screen.width;  
var scrHeight = screen.height;  
// The document.documentElement dimensions seem to be identical to  
// the screen dimensions on all the mobile browsers I've tested so far  
var elemWidth = document.documentElement.clientWidth;  
var elemHeight = document.documentElement.clientHeight;  
// We need to eliminate Symbian, Series 60, Windows Mobile and Blackberry  
// browsers for this quick and dirty check. This can be done with the user agent.  
var otherBrowser = (agent.indexOf("series60") != -1) || (agent.indexOf("symbian") != -1) || (agent.indexOf("windows ce") != -1) || (agent.indexOf("blackberry") != -1);  
// If the screen orientation is defined we are in a modern mobile OS  
var mobileOS = typeof orientation != 'undefined' ? true : false;  
// If touch events are defined we are in a modern touch screen OS  
var touchOS = ('ontouchstart' in document.documentElement) ? true : false;  
// iPhone and iPad can be reliably identified with the navigator.platform  
// string, which is currently only available on these devices.  
var iOS = (navigator.platform.indexOf("iPhone") != -1) ||  
        (navigator.platform.indexOf("iPad") != -1) ? true : false;  
// If the user agent string contains "android" then it's Android. If it  
// doesn't but it's not another browser, not an iOS device and we're in  
// a mobile and touch OS then we can be 99% certain that it's Android.  
var android = (agent.indexOf("android") != -1) || (!iOS && !otherBrowser && touchOS && mobileOS) ? true : false;  
  
document.write("<p><b>Screen width:</b> " + scrWidth +"px<br />" +  
 "<b>Screen height:</b> " + scrHeight + "px<br />" +  
 "<b>Document element width:</b> " + elemWidth +"px<br />" +  
 "<b>Document element height:</b> " + elemHeight + "px<br />" +  
 "<b>iOS device:</b> "+iOS+"<br />"+  
 "<b>Mobile OS:</b> "+mobileOS+"<br />"+  
 "<b>Touch OS:</b> "+touchOS+"<br />"+  
 "<b>Android device:</b> "+android+"</p>" +  
 "<p><b>User agent string:</b> "+navigator.userAgent+"</p>"  
 );  
</script>  
</body>  
</html>