var windowWidth = document.documentElement.clientWidth;
var windowHeight = document.documentElement.clientHeight;

if (document.documentElement.clientWidth < 1000) {
	document.write('<link href="smallscreen.css" rel="stylesheet" type="text/css" />');
}
else {
	document.write('<link href="standard.css" rel="stylesheet" type="text/css" />');
}