return DefaultTabController(
        length: 2,
        child: Scaffold(
          appBar: PreferredSize(
            child: AppBar(
              backgroundColor: Colors.greenAccent,
              bottom: TabBar(
                controller: tabController,
                tabs: [
                  Tab(
                    child: Text("Login"),
                  ),
                  Tab(
                    child: Text("Sign Up"),
                  ),
                ],
                indicatorColor: Colors.black,
              ),
              flexibleSpace: Container(
                decoration: BoxDecoration(
                  gradient: LinearGradient(
                    colors: [
                      Colors.red,
                      Colors.orange,
                    ],
                  ),
                ),
              ),
            ),
            preferredSize: Size.fromHeight(200.0),
          ),
          body: TabBarView(
            controller: tabController,
            children: [
              LoginApp(),
              SignUpApp(),
            ],
          ),
        ),
      );