text: import React from 'react';
  import { createStackNavigator } from 'react-navigation';
  import { HomeScreen } from './HomeScreen';
  import { LoginScreen } from './LoginScreen';
  
  const RootStack = createStackNavigator(
    {
      Login: {
        screen: LoginScreen,
        navigationOptions: () => ({
          headerTitle: 'Anmeldung',
          headerStyle: {
            backgroundColor: '#1976d2',
          },
          headerTintColor: '#fff',
        })
      },
      Home: {
        screen: HomeScreen,
        navigationOptions: () => ({
          headerTitle: 'Übersicht',
          headerStyle: {
            backgroundColor: '#1976d2',
          },
          headerTintColor: '#fff',
        })
      }
    },
    {
      initialRouteName: 'Home'
    }
  );
  
  export default class App extends React.Component {
    render() {  
      return (
        <RootStack />
      );
    }
  }