Code from the book isn't running

<!DOCTYPE html>
<html>

<head>
  <title>React Styling Using CSS</title>
  <script src="https://unpkg.com/[email protected]/dist/react.js"></script>
  <script src="https://unpkg.com/[email protected]/dist/react-dom.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/babel-core/5.8.23/browser.min.js"></script>
  <style>
    div div div {
      padding: 10px;
      margin: 10px;
      background-color: #ffde00;
      color: #333;
      display: inline-block;
      font-family: monospace;
      font-size: 32px;
      text-align: center;
    }
  </style>
</head>

<body>
  <div id="container"></div>

  <script type="text/babel">
    var Letter = React.createClass({
      render: function() {
          return (
            <div className="letter">
              {this.props.children}
            </div>
          );
        }
    });

    var destination = document.querySelector("#container");

    ReactDOM.render(
      <div>
        <Letter>A</Letter>
        <Letter>E</Letter>
        <Letter>I</Letter>
        <Letter>O</Letter>
        <Letter>U</Letter>
      </div>,
      destination
    );
  </script>
</body>

</html>

Help please. Why this code isn’t running? Can’t find any issues :frowning: