In the login.dart, there is a typo

[hyukjin0419]

Maybe that code should be right here. It is correct in github, but not in the code that presented in this -> https://codelabs.developers.google.com/codelabs/mdc-101-flutter#3

TextField( decoration: const InputDecoration( filled: true, labelText: 'Username', ), ), // spacer

Here the height should be 12.0, not 120.0

const SizedBox**(height: 120.0),** // [Password] TextField( decoration: const InputDecoration( filled: true, labelText: 'Password', ), obscureText: true, ),