docs: function () {
              var state = this.state,
                  fitWidth = this.calculateZoomValue(ZOOM_FIT_WIDTH),
                  fitHeight = this.calculateZoomValue(ZOOM_FIT_HEIGHT);
  
              // landscape
              if (state.widestPage.actualWidth > state.tallestPage.actualHeight) {
                  return Math.min(fitWidth, fitHeight);
              }
              // portrait
              else {
                  if (browser.mobile) {
                      return fitHeight;
                  }
                  // limit max zoom to 1.0
                  return Math.min(1, fitHeight);
              }
          }