parallax.js

$(window).scroll(function(e){
	parallax();
});


function parallax() {
	
	var scrolled = $(window).scrollTop();
    
    	//81% is the original top position of the element,
    	// which could be made into a variable onload instead
    	
 	$('#foo').css('top', 'calc(81% - ' + (scrolled * .2) + 'px)');
 
};