var scrollSpeed = 70;       // Speed in milliseconds
var step = 1;               // How many pixels to move per step
var current = 0;            // The current pixel row
var imageHeight = 1268;     // Background image height
var headerHeight = 230;     // How tall the header is. 
	
$(function(){ 
  	scrollBg();
});

function scrollBg() {      
	var restartPosition = imageHeight + headerHeight;
	current -= step;
	if (current == restartPosition){current = 0;}   
	$('#header').css("background-position","0 "+current+"px");
}
setInterval("scrollBg()", scrollSpeed);