Help! stuck at step 16 css colors

Tell us what’s happening:
Describe your issue in detail here.

  **Your code so far**
/* file: index.html */
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Colored Markers</title>
  <link rel="stylesheet" type="text/css" href="styles.css">
</head>
<body>
  <h1>CSS Color Markers</h1>
  <div class="container">
    <div class="markerclass1">
    </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 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/102.0.0.0 Safari/537.36

Challenge: Step 16

Link to the challenge:

Unfortunately, the project never introduces how to add more than one class to an element.

To add multiple classes to an element, you simply need to separate them by spaces for the value of the class attribute.

For example, if I wanted to add class names of color and blue to a p element, I would write:

<p class="color blue">Example of adding two classes to an element.</p>

Thanks a lot. Now I understand what they meant by add class one