React Native, change React Navigation header styling

I'm implementing React Navigation in my React Native app, and I'm wanting to change the background and foreground colors of the header. I have the following:

/**
 * Sample React Native App
 * https://github.com/facebook/react-native
 * @flow
 */

import React, { Component } from 'react';
import {
  AppRegistry,
  StyleSheet,
  Text,
  View
} from 'react-native';
import { StackNavigator } from 'react-navigation';

export default class ReactNativePlayground extends Component {

  static navigationOptions = {
    title: 'Welcome',
  };

  render() {
    return (
      <View style={styles.container}>
        <Text style={styles.welcome}>
          Welcome to React Native!
        </Text>
        <Text style={styles.instructions}>
          To get started, edit index.android.js
        </Text>
        <Text style={styles.instructions}>
          Double tap R on your keyboard to reload,{'\n'}
          Shake or press menu button for dev menu
        </Text>
      </View>
    );
  }

}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#F5FCFF',
  },
  welcome: {
    fontSize: 20,
    textAlign: 'center',
    margin: 10,
  },
  instructions: {
    textAlign: 'center',
    color: '#333333',
    marginBottom: 5,
  },
});

const SimpleApp = StackNavigator({
  Home: { screen: ReactNativePlayground }
});

AppRegistry.registerComponent('ReactNativePlayground', () => SimpleApp);

By default the background color of the heading is white, with a black foreground. I've also looked at the documentation for React Navigation but I'm not able to find where it shows how to set the styling. Any help?