Template source: responsive/snippet.html

<script type="text/javascript">
	(function () {
		var dpr = ('devicePixelRatio' in window) ? window.devicePixelRatio :
			(('deviceXDPI' in window) && ('logicalXDPI' in window)) ? (window.deviceXDPI / window.logicalXDPI) : 1;

		var	clientInfo = screen.width + ":" + screen.height + ':' + dpr;
		document.cookie = "{{ cookie_name }}=" + clientInfo + "; max-age={{ cookie_age }}; expires={{ cookie_expires }}; path=/";
		if (navigator.cookieEnabled) document.location.reload(true);
	})();
</script>