Learn CSS Colors by Building a Set of Colored Markers - Step 16

I keep writing it wrong,please how do I add class one to this div element?
  **Your code so far**
/* file: index.html */
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Colored Markers</title>
  <link rel="stylesheet" href="styles.css">
</head>
<body>
  <h1>CSS Color Markers</h1>
  <div class="container">
    <div class="marker">
    </div>
    <div class="marker">
    </div>
    <div class="marker">
    </div>
  </div>
</body>
</html>
/* file: styles.css */
h1 {
text-align: center;
}

.marker {
width: 200px;
height: 25px;
background-color: red;
margin: 10px auto;
}

  **Your browser information:**

User Agent is: Mozilla/5.0 (Linux; Android 11; TECNO CE7j) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.210 Mobile Safari/537.36

Challenge: Learn CSS Colors by Building a Set of Colored Markers - Step 16

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