javascript - On scroll, how to make a div in the background move up, while the div on top of it moves in the opposite direction? -

here website: http://kingston20x15.com/

what jquery should looking @ try , blocks in background move in opposite direction vertically blocks in front of text?

so far i've been trying hack fiddle unsuccessfully:

http://jsfiddle.net/5uutv/1/

var winheight = $(window).innerheight(); $(document).ready(function () {     $(".panel").height(winheight);     $("body").height(winheight*$(".panel").length); });  $(window).on('scroll',function(){     $(".panelcon").css('bottom',$(window).scrolltop()*-1); });