React Js Add Class to Element by ID

<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8" />
  <script src="https://unpkg.com/react@17.0.2/umd/react.development.js"></script>
  <script src="https://unpkg.com/react-dom@17.0.2/umd/react-dom.development.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/babel-standalone/6.26.0/babel.min.js"></script>
</head>
<body>
  <div id="app"></div>
  <script type="text/babel">
    const { useState } = React;
    function App() {
      const addClassToElement = () => {
        const element = document.getElementById('myElement');

if (element) {
          element.classList.add('my-new-class');
        }
      };

return (
        <div className='container'>
          <h3>React Js Add Class to Element by ID</h3>
          <div id="myElement">
            Press the button below to include a class.
          </div>
          <button onClick={addClassToElement}>Add Class</button>
        </div>
      );

}

ReactDOM.render(<App />, document.getElementById("app"));
  </script>

/* Styles for the myElement class */
    .my-new-class {
      margin-bottom: 20px;
      font-size: 18px;
      font-weight: bold;
      color: #f44336;
      background-color: #ccc;
      padding: 20px;
      border-radius: 5px;
    }

/* Styles for the button */
    button {
      background-color: #4caf50;
      color: white;
      border: none;
      padding: 10px 20px;
      border-radius: 5px;
      cursor: pointer;
      transition: background-color 0.3s ease;
    }

button:hover {
      background-color: #45a049;
    }
  </style>
</body>

</html>