var viewportwidth;

// the more standards compliant browsers (mozilla/netscape/opera/IE7) use window.innerWidth and window.innerHeight

if (typeof window.innerWidth != 'undefined') {
	viewportwidth = window.innerWidth, viewportheight = window.innerHeight
}

// IE6 in standards compliant mode (i.e. with a valid doctype as the first line in the document)

else if (typeof document.documentElement != 'undefined' && typeof document.documentElement.clientWidth != 'undefined' && document.documentElement.clientWidth != 0) {
	viewportwidth = document.documentElement.clientWidth, viewportheight = document.documentElement.clientHeight
}

// older versions of IE

else {
	viewportwidth = document.getElementsByTagName('body')[0].clientWidth, viewportheight = document.getElementsByTagName('body')[0].clientHeight
}

// document.write('<span style="color: white;"><p>Your viewport width is '+viewportwidth+'x'+viewportheight+'</p></span>');