code: function( config ) {
          var hScale = window.innerHeight / config.height,
              wScale = window.innerWidth / config.width,
              scale = hScale > wScale ? wScale : hScale;
  
          if ( config.maxScale && scale > config.maxScale ) {
              scale = config.maxScale;
          }
  
          if ( config.minScale && scale < config.minScale ) {
              scale = config.minScale;
          }
  
          return scale;
      }
docs: `computeWindowScale` counts the scale factor between window size and size defined for the presentation in the config.