code: private int getNavigationBarOffset() {
          int result = 0;
          Resources resources = mHoldingActivity.getResources();
          if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
              int resourceId = resources.getIdentifier("navigation_bar_height", "dimen", "android");
              if (resourceId > 0) {
                  result = resources.getDimensionPixelSize(resourceId);
              }
          }
          return result;
      }
docs: Retrieve offset introduce by the navigation bar.
  
  @return bottom offset due to navigation bar.