React Js Hide Alert after 5 seconds

<!DOCTYPE html>
<html>

<body>
  <div id="app"></div>
  <script type="text/babel">
    const { useState } = React;
    function App() {
      const [show, setShow] = useState(true);
      const [message, setMessage] = useState('This is Warning alert');
      const timer = setTimeout(() => { setShow(false); }, 5000);
      return (
        <div className='container'>
          <h2>React Js Hide Alert After 5 Seconds or onclick</h2>
          {show && (
            <div className="alert alert-warning">
              {message}
              <button onClick={() => setShow(false)} className="close-btn">&times;</button>
            </div>
          )}
          <button onClick={() => setShow(true)} className="show-alert-btn">Show Alert</button>

</div>
      );
    }

ReactDOM.render(<App />, document.getElementById('app'));
  </script>
  <style>
    .container {
      text-align: center;
      box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.12), 0 2px 4px 0 rgba(0, 0, 0, 0.24);
      width: 600px;
      margin: 0 auto;
      padding: 20px;
    }

.alert {
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 15px;
      border-radius: 5px;
      font-size: 16px;
      background-color: #fff3cd;
      border: 1px solid #ffeeba;
      color: #856404;
      position: relative;
      animation-fill-mode: forwards;
    }

.alert-warning {
      background-color: #fff3cd;
      border-color: #ffeeba;
      color: #856404;
    }

.close-btn {
      font-size: 22px;
      font-weight: bold;
      color: #856404;
      background-color: transparent;
      border: none;
      cursor: pointer;
      position: absolute;
      top: 50%;
      right: 10px;
      transform: translateY(-50%);
    }

.close-btn:hover {
      color: #6A5003;
    }

.show-alert-btn {
      padding: 10px 20px;
      font-size: 16px;
      background-color: #3498db;
      color: #fff;
      border: none;
      border-radius: 5px;
      margin-top: 10px;
      cursor: pointer;
      transition: background-color 0.3s ease;
    }

/* Hover effect */
    .show-alert-btn:hover {
      background-color: #2980b9;
    }
  </style>

</body>

</html>