The height of the NavigationBar itself.
If this is used in Scaffold.bottomNavigationBar and the scaffold is full-screen, the safe area padding is also added to the height automatically.
The height does not adjust with ThemeData.visualDensity or MediaQueryData.textScaleFactor as this component loses usability at larger and smaller sizes due to the truncating of labels or smaller tap targets.
If null, NavigationBarThemeData.height is used. If that is also null, the default is 80.
final double? height;