Learn Responsive Web Design by Building a Piano - Step 6 plz i need help as fast as possible

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Describe your issue in detail here.
Hi could someone tell me what they think is wrong with this 'cause I cant figure it out

Your code so far

<!-- 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>
    <div id="piano">
      <div class="keys">
        <div class="key"  class="black--key"></div>
        <div class="key" class="black--key"></div>
        <div class="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>
  </body>
</html>
/* file: styles.css */

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.0.0 Safari/537.36

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

Link to the challenge:

Hi! Do you remember the colored marker lessons? In those lessons you are shown how to add another class to the same css element. I would suggest reviewing them.

You do not have to make a new class attribute and value, you have to add the new class value to the existing class attribute.