styletron

app.js

import React, { Component } from 'react';
import logo from './logo.svg';
import './App.css';

import {styled} from 'styletron-react';

const Panel = styled('div', {
  backgroundColor: 'lightblue',
  fontSize: '12px',
  '@media (max-width: 768px)': {
    fontSize: '24px'
  },
});

const Next = styled('div', (props) => ({
  backgroundColor: props.color ? props.color : 'red',
}))

class App extends Component {
  render() {
    return (
      <div className="App">
        <Panel>Hello World</Panel>
        <Next>Hey</Next>
        <Next color={"green"}>OK</Next>
        <div className="App-header">
          <img src={logo} className="App-logo" alt="logo" />
          <h2>Welcome to React</h2>
        </div>
        <p className="App-intro">
          To get started, edit <code>src/App.js</code> and save to reload.
        </p>
      </div>
    );
  }
}

export default App;

index.js

import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import registerServiceWorker from './registerServiceWorker';

import Styletron from 'styletron-client';
import {StyletronProvider} from 'styletron-react';

ReactDOM.render(
  <StyletronProvider styletron={new Styletron()}>
    <App/>
  </StyletronProvider>,
  document.getElementById('root')
);
registerServiceWorker();