Ширина закусочной трепетана
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!'),
),
);
Sore Serval