How do I hide the shadow under react-navigation headers?

Question

How do I hide the shadow under react-navigation headers?
They look like this.

Answer 1

This works for me:

export const AppNavigator = StackNavigator(
    {
      Login: { screen: LoginScreen },
      Main: { screen: MainScreen },
      Profile: { screen: ProfileScreen },
    },
    navigationOptions: {
        headerStyle: {
            elevation: 0,
            shadowOpacity: 0,
        }
    }
);

or

export const AppNavigator = StackNavigator(
    {
      Login: { screen: LoginScreen },
      Main: { screen: MainScreen },
      Profile: { screen: ProfileScreen },
    },
    header: {
        style: {
            elevation: 0, //remove shadow on Android
            shadowOpacity: 0, //remove shadow on iOS
        }
    }
);