Specifies the height mode of the AppBar component which defines the height of the AppBar.
The possible values for this property are as follows:
- Regular - Specifies default height for the AppBar.
- Prominent - Specifies longer height for the AppBar to show the longer titles and images, or to provide a stronger presence.
- Dense - Specifies compressed (short) height for the AppBar to accommodate all the app bar content in a denser layout.