text: /**
   *
   *
   * @param backgroundClass   The class of the element with the background that you wish to expand. Assumes there's only one
   *                          matching element, or that it is the first one
   * @param logging           True or false. If true, the console displays the current image size as a percentage
   * @param divider           How much to divide the windows Y-axis scroll position by to get the scale - smaller numbers give a bigger scale
   */
  
  function expandBackground(backgroundClass, logging, divider) {
  
      logging = logging || false;
      divider = divider || 50;
      var scrollY = 0;
      var elWithBackgroundImg = document.getElementsByClassName(backgroundClass)[0];
      var maxHeight = elWithBackgroundImg.offsetHeight;
  
      function stretchBG(scroll_pos) {
          var scale = 100 + (scroll_pos / divider);
          elWithBackgroundImg.style.backgroundSize = scale  + "%";
          if (logging) console.log("background size: ", scale + "%");
      }
  
      window.addEventListener('scroll', function (e) {
          scrollY = window.scrollY;
          if (window.pageYOffset < maxHeight) {
              window.requestAnimationFrame(function () {
                  stretchBG(scrollY);
              });
          }
      });
  
  }
  