anchor.diff:        ul {
           /* Same width as `container-fluid` */
           padding-left: 15px;
  +      }
  +
  +      /* Built on http://codepen.io/twolfson/pen/XjQdKL */
  +      .loading {
  +        /* Default to low opacity for browsers without keyframe support */
  +        opacity: 0.3;
  +
  +        /* Add our animation */
  +        /* https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Animations/Using_CSS_animations */
  +        animation-duration: 0.5s;
  +        animation-name: loading;
  +        animation-iteration-count: infinite;
  +        animation-direction: alternate;
  +        animation-timing-function: linear;
  +      }
  +
  +      @keyframes loading {
  +        from { opacity: 0.3; }
  +        to { opacity: 0.4; }
         }
       script(src="https://code.jquery.com/jquery-3.1.1.min.js", integrity="sha256-hVVnYaiADRTO2PzUGmuLJr8BLUSjGIZsDYGmIJLv2b8=", crossorigin="anonymous")
       script(src="https://cdn.rawgit.com/twbs/bootstrap/v3.3.7/dist/js/bootstrap.min.js")
  
positive.code:         var btnEl = evt.target;
          var $imgSet = $(btnEl).closest('[data-image-set]');
          var imgSetId = $imgSet.data('image-set');
          assert.strictEqual($imgSet.length, 1);
  
          // Find the current image
          var $currentImg = $imgSet.find('[data-compare-type="current"]');
          assert.strictEqual($currentImg.length, 1);
  
          // Run acceptance function
        });
  
      script.
  
negative.code:         // TODO: If there is an error, reset our status
  
          // TODO: When loading completes, remove loading state and update image references
          setTimeout(function () {
            $diffImg.removeClass('loading');
            $refImg.removeClass('loading');
            cachebustImg($diffImg);
            cachebustImg($refImg);
          }, 1000);
        }
  
        // Define base64 content helper
        function getBase64Content(imgEl) {
          // TODO: Complete base64 extraction
          return '';
        }
  
        // Set up image acceptance binding
  