behavior: SnackBarBehavior.floating,
margin: const EdgeInsets.fromLTRB(15.0, 5.0, 15.0, 10.0), //It can not be used if width is specified.
padding: const EdgeInsets.all(16.0),
ScaffoldMessenger.of(context).showSnackBar(
SnackBar(
behavior: SnackBarBehavior.floating, // default SnackBarBehavior.fixed.
width: 250.0, // It can not be used if margin is specified.
content: const Text('Awesome!'),
),
);