Parallax Background

http://xenforo.com/community/resources/parallax-background.2566/

https://XenoGamers.org/

/* Firefox super responsive scroll (c) Keith Clark - MIT Licensed */
(function(e){var t=e.documentElement;if("MozAppearance"in t.style){var n=t.clientWidth;t.style.overflow="scroll";n-=t.clientWidth;t.style.overflow="";var r=e.createEvent("UIEvent");r.initEvent("scroll",true,true);function i(){e.dispatchEvent(r)}e.addEventListener("mousedown",function(r){if(r.clientX>t.clientWidth-n){e.addEventListener("mousemove",i,false);e.addEventListener("mouseup",function(){e.removeEventListener("mouseup",arguments.callee,false);e.removeEventListener("mousemove",i,false)},false)}},false);e.addEventListener("DOMMouseScroll",function(e){if(!e.ctrlKey&&!e.shiftKey){t.scrollTop+=e.detail*16;i.call(this,e);e.preventDefault()}},false)}})(document);

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

function parallax() {
  var scrolled = $(window).scrollTop();
  $('#XenForo').css('background-position', '0px ' + -(scrolled * 0.2) + 'px');
}

background-attachment: fixed;