I dont undrestand where i did mistake

Tell us what’s happening:

Your code so far


<link href="https://fonts.googleapis.com/css?family=Lobster" rel="stylesheet" type="text/css">
<style>
  .thick-green-border {
    border-color: green;
    border-width: 10px;
    border-style: solid;
  }
  .red-text { 
    color: red;
  }

  h2 {
    font-family: Lobster, monospace;
  
  p {
    font-size: 16px;
    font-family: monospace;
  }

  .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-boarder"src="https://bit.ly/fcc-relaxing-cat" alt="A cute orange cat lying on its back."></a>
  
  <div>
    <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="/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>

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.132 Safari/537.36 OPR/63.0.3368.71.

Link to the challenge:
https://learn.freecodecamp.org/responsive-web-design/basic-css/add-borders-around-your-elements/

It looks like you just misspelled border when adding you class to the image.