I made the test correctly and the silver background appear but it doesn't take pass

<link href="https://fonts.googleapis.com/css?family=Lobster" rel="stylesheet" type="text/css">

<style>

  .red-text {

    color: red;

  }

.silver-background {

    

    background-color: silver ;

    

  }

  h2 {

    font-family: Lobster, monospace;

  }

  p {

    font-size: 16px;

    font-family: monospace;

  }

  .thick-green-border {

    border-color: green;

    border-width: 10px;

    border-style: solid;

    border-radius: 50%;

  }

  .smaller-image {

    width: 100px;

  }

</style>

<h2 class="red-text">CatPhotoApp</h2>

<main>

  <p class="red-text">Click here to view more <a href="#">cat photos</a>.</p>

  <a href="#"><img class="smaller-image thick-green-border" src="https://bit.ly/fcc-relaxing-cat" alt="A cute orange cat lying on its back."></a>

  <div class="silver-background">

    <p>Things cats love:</p>

    <ul>

      <li>cat nip</li>

      <li>laser pointers</li>

      <li>lasagna</li>

    </ul>

    <p>Top 3 things cats hate:</p>

    <ol>

      <li>flea treatment</li>

      <li>thunder</li>

      <li>other cats</li>

    </ol>

  </div>

  <form action="https://freecatphotoapp.com/submit-cat-photo">

    <label><input type="radio" name="indoor-outdoor" checked> Indoor</label>

    <label><input type="radio" name="indoor-outdoor"> Outdoor</label><br>

    <label><input type="checkbox" name="personality" checked> Loving</label>

    <label><input type="checkbox" name="personality"> Lazy</label>

    <label><input type="checkbox" name="personality"> Energetic</label><br>

    <input type="text" placeholder="cat photo URL" required>

    <button type="submit">Submit</button>

  </form>

</main>

this is the code and i don’t know what to do

Your html doesn’t contain class attribute, which means that the style you have applied to the class won’t affect the html.

I’ve edited your post for readability. When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make it easier to read.

You can also use the “preformatted text” tool in the editor (</>) to add backticks around text.

See this post to find the backtick on your keyboard.
Note: Backticks (`) are not single quotes (’).

no, I have added the class element , look the div element ,they ask me for a div element of background silver color, it appears on my screen ,in the results , but it doesn’t let me pass .

What is the test’s “error message”?

The reason the test is failing is the line:
background-color: silver ;

remove the space between silver and the ; and it should pass.

I’m not a CSS expert but I believe your solution is valid CSS and this is an issue with the parsing system rather than an problem in your code.