load "http://www.ilovejs.net/lab/css.php" first,but it will take two seconds to response. chage the background at div.

and then load "http://www.ilovejs.net/lab/load.css". chage the font-size and font-family

var head = document.getElementsByTagName("head")[0];

var style = document.createElement('style');
//加载css.php文件，需要2秒之后才会返回响应内容
style.textContent = '@import "http://www.ilovejs.net/lab/css/css.php"';
style.rel="stylesheet";

var fi = setInterval(function() {
  try {
    style.sheet.cssRules; // MAGIC: only populated when file is loaded

	//如果css.php加载完毕，那么再加载一个css文件。
	var s = document.createElement("style");
	s.textContent = '@import "http://www.ilovejs.net/lab/css/load.css"';
	s.rel = "stylesheet";

	var t = setInterval(function(){
	  try{
	    s.sheet.cssRules;
		alert("CSS loaded");
	  }catch(e){}

	  clearInterval(t);
	},10);

	head.appendChild(s);

    clearInterval(fi);

  } catch (e){}

}, 10);  

head.appendChild(style);