gistfile1.js

$(function(){
  (function() {
    var iphone = false;

    var supportsFixed = function () {
      var ua = navigator.userAgent;

      if (/iphone|ipod|ipad/i.test(ua)) {
        iphone = true;
        return !(/OS [1-4]/i.test(ua));
      }

      if (/android/i.test(ua)) {
        var version = parseFloat(ua.match(/Android (\d).*/i)[1], 10);
        return !(version < 3);
      }

      return true;
    }

    var fixSliderPosition = function() {
      var slider = $("#qContent");
      if (!slider.length) {
        setTimeout(fixSliderPosition, 200);
        return;
      }
  
      slider.show();
      slider.height(110);
      
      setInterval(function() {
        var top = ($(window).scrollTop() + $(window).height()) - slider.height();
        if (iphone) top += 40;
        slider.css("top", top);
      }, 10);
    }

    if (!supportsFixed()) {
      fixSliderPosition();
    }
  })();
})