<div id="content"></div>
button {
    background: red;
    border-radius: 8px;
    color: white;
}

.small {
    height: 40px;
    width: 80px;
}

.medium {
    height: 50px;
    width: 100px;
}

.large {
    height: 60px;
    width: 120px;
}
class Application extends React.Component {
  render() {
    return (
      <div>
        <button className="small">Click Me</button>
        <button className="large">Click Me</button>
      </div>
    )
  }
}

ReactDOM.render(<Application />, document.getElementById('content'));
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External CSS

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External JavaScript

  1. https://cdnjs.cloudflare.com/ajax/libs/react/15.4.2/react.min.js
  2. https://cdnjs.cloudflare.com/ajax/libs/react/15.4.2/react-dom.min.js
  3. https://unpkg.com/styled-components/dist/styled-components.min.js