inserida a fonte, e criada a tela de login_screen.dart

lib/widgets/snackBars.dart

@@ -0,0 +1,20 @@
+import 'package:flutter/material.dart';
+
+void showSnackBar(BuildContext context, String text,Color colors){
+
+  final snackbar = SnackBar(
+    backgroundColor: colors,
+    content: Row(
+      children: [
+        Icon(Icons.info_outline,color: Colors.white),
+        SizedBox(width: 20),
+        Expanded(
+          child: Text(text,
+            style: TextStyle(fontSize: 16),),
+        ),
+      ],
+    ),
+  );
+
+  ScaffoldMessenger.of(context).showSnackBar(snackbar);
+}