<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>CodePen</title>
</head>
<body>
  <div id="container"></div>
</body>
</html>
class TweetBox extends React.Component {
  handleChange = (e) => {
    console.log(e.target.value);
  };

  render() {
    return (
      <div className="card bg-light">
        <div className="card-body text-right">
          <textarea className="form-control" onChange={this.handleChange}></textarea>
          <br/>
          <button className="btn btn-primary">Tweet</button>
        </div>
      </div>
    );
  }
};

ReactDOM.render(
  <TweetBox />,
  document.getElementById("container")
);
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External CSS

  1. https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.1.3/css/bootstrap.min.css

External JavaScript

  1. https://cdnjs.cloudflare.com/ajax/libs/react/16.7.0/umd/react.production.min.js
  2. https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.7.0/umd/react-dom.production.min.js