Add the following to the navigationOptions header style.
const AppNavigation = StackNavigator(
{
'The First Screen!': { screen: FirstScreen },
},
{
navigationOptions: {
header: {
style: {
elevation: 0, // remove shadow on Android
shadowOpacity: 0, // remove shadow on iOS
},
},
},
},
);
The documentation isn't great yet, but you can learn about navigationOptions in the React Navigation Docs.