Style.js

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

export default class LotsOfStyles extends Component {
  render() {
    return (
      <View style={styles.greybox}>
        <Text>Lorem Ipsum</Text>
      </View>
    );
  }
}

const styles = StyleSheet.create({
  greybox: {
    backgroundColor: #e0e0e0,
    width: 320px;
    height: 240px;
    font: 900 24px Georgia;
  }
})

// skip this line if using Create React Native App
AppRegistry.registerComponent('AwesomeProject', () => LotsOfStyles);