$(document).ready(function(){
var n = 11;
var i = Math.floor(Math.random() * n);
	
	CSSFILE = new Array(n-1);
	CSSFILE[0] = 'img/background6.jpg';
	CSSFILE[1] = 'img/background9.jpg';
	CSSFILE[2] = 'img/background10.jpg';
	CSSFILE[3] = 'img/background11.jpg';
	CSSFILE[4] = 'img/background12.jpg';
	CSSFILE[5] = 'img/background13.jpg';
	CSSFILE[6] = 'img/background14.jpg';
	CSSFILE[7] = 'img/background15.jpg';
	CSSFILE[8] = 'img/background17.jpg';
	CSSFILE[9] = 'img/background18.jpg';
	CSSFILE[10] = 'img/background19.jpg';
	
	$("#content").css("background-image" , "url('" + CSSFILE[i] + "')");
	
});