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

The following works for me as the original Stylesheet uses "borderBottomWidth" on iOS:

const navigator = StackNavigator(screens, {
  navigationOptions: {
    headerStyle: {
      elevation: 0,
      shadowOpacity: 0,
      borderBottomWidth: 0,
    }
  }
});