rndBG = function() {
	var imgArray = new Array('assets/content_bg_1.jpg','assets/content_bg_2.jpg','assets/content_bg_4.jpg','assets/content_bg_5.jpg','assets/content_bg_6.jpg');
	document.getElementById("content").style.backgroundImage = ('url(' + imgArray[Math.floor(imgArray.length * Math.random())] + ')');
}
if (window.attachEvent) window.attachEvent("onload", rndBG); else window.onload = rndBG;