added themes

lib/theme.dart

@@ -0,0 +1,15 @@
+import 'package:flutter/material.dart';
+
+ThemeData get lightTheme => ThemeData.from(colorScheme: _lightColorScheme);
+
+ThemeData get darkTheme => ThemeData.from(colorScheme: _darkColorScheme);
+
+ColorScheme get _darkColorScheme => ColorScheme.fromSeed(
+  seedColor: Colors.deepPurple,
+  brightness: Brightness.dark,
+);
+
+ColorScheme get _lightColorScheme => ColorScheme.fromSeed(
+  seedColor: Colors.deepPurple,
+  brightness: Brightness.light,
+);