[SOLVED] I want button like a this. but I can not set border or width

I want like a this button but I can not make it

Please tell me that how to make about

I did tryed code

ElevatedButton(
style: ElevatedButton.styleFrom(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(30)),
backgroundColor: Colors.lightBlue[400],
side:BorderSide(width: 2, color: Colors.black)),

result

Container(
  height: 50,
  width: 200,
  decoration: BoxDecoration(
    color: Color(0xff92fcd1),
    border: Border.all(color: Colors.black),
    borderRadius: BorderRadius.circular(100),
    boxShadow: <BoxShadow>[
      BoxShadow(
        color: Colors.black,
        offset: Offset(2.5, 2.5),
        spreadRadius: 0.1
      )
    ], 
  ),
  child: Center(
    child: Text('LOGIN'),
  )
),