main.diff

       title: 'Flutter Demo',
       theme: ThemeData(
         primarySwatch: Colors.blue,
+        pageTransitionsTheme: const PageTransitionsTheme(builders: {
+          TargetPlatform.android: CupertinoPageTransitionsBuilder(),
+          TargetPlatform.iOS: FadeUpwardsPageTransitionsBuilder(),
+          TargetPlatform.fuchsia: CupertinoPageTransitionsBuilder(),
+          TargetPlatform.linux: CupertinoPageTransitionsBuilder(),
+          TargetPlatform.windows: CupertinoPageTransitionsBuilder(),
+          TargetPlatform.macOS: CupertinoPageTransitionsBuilder(),
+        }),
       ),
       initialRoute: '/',
       routes: {