<div id="app"></div>
body {
  width: 100vw;
  height: 100vh;
  padding: 2vw;
}
View Compiled
class Title extends React.Component {
  render () {
    return (
      <h1>React 小书</h1>
    )
  }
}

class Header extends React.Component {
  render () {
    return (
      <div>
        <Title />
      </div>
    )
  }
}

ReactDOM.render(
  <Header />,
  document.getElementById('app')
)
View Compiled

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

  1. https://cdnjs.cloudflare.com/ajax/libs/react/15.6.1/react.min.js
  2. https://cdnjs.cloudflare.com/ajax/libs/react/15.6.1/react-dom.min.js