$(document).ready(function(){
	var listItem=$("#changeBtn>li");					   
	
	
	var maxTimes=listItem.size();
    var picNum=0;
	
	changeBackground=function(){
		if(picNum>=maxTimes){ picNum=0; }
		//$("#content").fadeIn('slow');   
		$("#content").fadeIn(1500); 
		 //$("#content").fadeTo("slow", 1);		
		//$("#content").css({'background':"url('images/content_BG'+picNum+'.png')"});
		$("#content").css({ 'background-image':"url(images/content_BG"+picNum+".png)"});
		$("#changeBtn>li").removeClass(); 
		listItem[picNum].className="active";
		picNum++;

	}
	
	setInterval("changeBackground()",3000);
    
});