Left-nav.js

//the function 
jQuery.fn.paralaxical = function (speed){
	var theOffset;
	if($(this).hasClass('left-nav-fixed')){
		var lastOffset = Number($(this).attr('data-last-offset-top'));
		var negativespeed = speed*-1;
		var thetop = $(this).position().top;
		var thebottom = thetop + $(this).height();
		if( $(this).height() + leftNavTopPosition > $(window).height() ){//yes the nav is larger than the page
			if($(this).offset().top > lastOffset && thebottom > $(window).height()){//we are scrolling down
				theOffset = negativespeed;
			}else if($(this).offset().top < lastOffset && thetop < 67){//we are scrolling up
				theOffset = speed;
			}
		}
	}
	$(this).offset({top: $(this).offset().top+theOffset});
	$(this).attr('data-last-offset-top', $(this).offset().top);
};

//keep track of where the nav is in the world
$('.left-nav-wrapper').attr('data-last-offset-top', leftNavTopPosition); 

//add the function to the scroll listener 
$(window).on('scroll', function () {
	$('.left-nav-wrapper').paralaxical(3);
}

//in toggleFixedLeftNav comment out the autoclose lines 
//$('.nav-left-list').removeClass('leftnav-open'); // comment in order to prevent autoclose
//$('.nav-list-l1').removeClass('leftnav-submenu-open'); // comment in order to prevent autoclose