window.onload = function() {
	bg = document.getElementById('header-step');
	//bg = bg.style.background;
	
	num = parseInt( Math.floor( ( Math.random() * 4 ) +1 ) );
	
	new_bg = "url(images/header/hdr-bg" + ((num < 10)?"0"+num:num) + ".jpg)";
	//alert( new_bg );
	bg.style.backgroundImage = new_bg;
}