function screensizer () {
	var screenwidth=0;
	if( typeof( window.innerWidth ) == 'number' ) {
		//Non-IE
		screenwidth = window.innerWidth;
	} else if( document.documentElement && ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) {
		//IE 6+ in 'standards compliant mode'
		screenwidth = document.documentElement.clientWidth;
	} else if( document.body && ( document.body.clientWidth || document.body.clientHeight ) ) {
		//IE 4 compatible
		screenwidth = document.body.clientWidth;
	}
	if ((screenwidth<=640)) {
		setActiveStyleSheet('640x480');
	}else if ((screenwidth>640)&&(screenwidth<=800)) {
		setActiveStyleSheet('800x600');
	}else{
		setActiveStyleSheet('1024x768');
	}
	return false;
}
function setActiveStyleSheet(title) {
  var i, a, main;
  for(i=0; (a = document.getElementsByTagName("link")[i]); i++) {
    if(a.getAttribute("rel").indexOf("style") != -1 && a.getAttribute("title")) {
      a.disabled = true;
      if(a.getAttribute("title") == title) a.disabled = false;
    }
  }
}