React Js Add Multiple Class to Element

<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8" />
  <script src="https://cdnjs.cloudflare.com/ajax/libs/react/17.0.2/umd/react.development.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/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">
    function App() {
      const multipleClassNames = 'class1 class2 class3';

return (
        <div className='container'>
          <div className={multipleClassNames}>
            React Js Add Multiple Css to Element
          </div>
        </div>

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

.container {
      margin: 0 auto;
      width: 600px;
      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);
      padding: 20px;
    }

/* styles.css */
    .class1 {
      background-color: lightblue;
      color: black;
      font-size: 16px;
    }

.class2 {
      /* Add styles for class2 */
      font-weight: bold;
      padding:20px
    }

.class3 {
      /* Add styles for class3 */
      border: 2px solid red;
    }
  </style>
</body>

</html>

 
<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8" />
  <script src="https://cdnjs.cloudflare.com/ajax/libs/react/17.0.2/umd/react.development.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/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">
    function App() {
      const multipleClassNames = 'class1 class2 class3';
​
      return (
        <div className='container'>
          <div className={multipleClassNames}>
            React Js Add Multiple Css to Element
          </div>
        </div>
​
      );
    }
    ReactDOM.render(<App />, document.getElementById("app"));
  </script>
​
  <style>
    * {
      box-sizing: border-box;
    }
​
    .container {
      margin: 0 auto;
      width: 600px;
      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);
      padding: 20px;
    }
​
    /* styles.css */
    .class1 {
      background-color: lightblue;
      color: black;
      font-size: 16px;
    }
​
    .class2 {
      /* Add styles for class2 */
      font-weight: bold;
      padding:20px
    }
​
    .class3 {
      /* Add styles for class3 */
      border: 2px solid red;
    }
  </style>
</body>
​
</html>