jQuery.fn.delay = function(time,func){
	this.each(function(){
		setTimeout(func,time);
	});
	
	return this;
};

$(document).ready(function(){	
		$(this).delay(750,function(){
			var div_height = $("#nav_bottom").outerHeight(); 
			var offset = $("#nav_bottom").offset();			
			var div_top = offset.top;	
			$("#footer_bg").css({ 'height' : div_height , 'top' : div_top});
		});	
});