Learn Responsive Web Design by Building a Piano - Step 6

Please what am I doing wrong here, Is it wrong to add another"class" before the “black–key” or do I have less or more than the required seven “div” elements ? Help needed. Thank you.

 <div class="keys">
        <div class="key"></div>
        <div class="key" class="black--key"></div>
        <div class="key" class="black--key"></div>
        <div class="key"></div>
        <div class="key" class="black--key"></div>
        <div class="key" class="black--key"></div>
        <div class="key" class="black--key"></div>
      </div>
<!-- file: index.html -->
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <title>Piano</title>
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  </head>
  <body>

<!-- User Editable Region -->

    <div id="piano">
      <div class="keys">
        <div class="key"></div>
        <div class="key" class="black--key"></div>
        <div class="key" class="black--key"></div>
        <div class="key"></div>
        <div class="key" class="black--key"></div>
        <div class="key" class="black--key"></div>
        <div class="key" class="black--key"></div>
      </div>
    </div>

<!-- User Editable Region -->

  </body>
</html>
/* file: styles.css */

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/111.0

Challenge: Learn Responsive Web Design by Building a Piano - Step 6

Link to the challenge:

If you have to add more than one class to an html element, follow the rule:

<element class="value1 value2 value3"></element>