var cssId = "appCss";  // you could encode the css path itself to generate id..
if (!document.getElementById(cssId))
{
	var time  = Math.floor(Date.now() / 1000);
	var r  = Math.floor(Math.random()*1000000);
	var head  = document.getElementsByTagName("head")[0];
	var link  = document.createElement("link");
	link.id   = cssId;
	link.rel  = "stylesheet";
	link.type = "text/css";
	link.href = '/assets/app/app.2b911a97.css?' + time + "." + r;
	link.media = "all";
	head.appendChild(link);
}