Ditch Custom CSS for Bootstrap...?

Your h2 element should no longer have the class red-text.
Your h2 element should now have the class text-primary.
Add the img-responsive class to your top image.

That is all I’m missing ^ to move forward to next objective.
I’m newbie at this but love learning more about it, could anyone help me out/ pointers?

Your code so far

<link href="https://fonts.googleapis.com/css?family=Lobster" rel="stylesheet" type="text/css">
<style>
  
  {
      color: red;
  }

  h2 {
    font-family: Lobster, Monospace;
    class: text-primary;
  }

  p {
    font-size: 16px;
  }

  .thick-green-border {
    border-color: green;
    border-width: 10px;
    border-style: solid;
    border-radius: 50%;
  }

  .smaller-image {
    width: 100px;
  }
</style>

<div class="container-fluid">
  <h2 class="red-text text-center">CatPhotoApp</h2>

  <p>Click here for <a href="#">cat photos</a>.</p>

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

  <img src="https://bit.ly/fcc-running-cats" class="img-responsive" alt="Three kittens running towards the camera. ">
  <div class="row">
    <div class="col-xs-4">
      <button class="btn btn-block btn-primary">Like</button>
    </div>
    <div class="col-xs-4">
      <button class="btn btn-block btn-info">Info</button>
    </div>
    <div class="col-xs-4">
      <button class="btn btn-block btn-danger">Delete</button>
    </div>
  </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>
  <form action="/submit-cat-photo">
    <label><input type="radio" name="indoor-outdoor"> Indoor</label>
    <label><input type="radio" name="indoor-outdoor"> Outdoor</label>
    <label><input type="checkbox" name="personality"> Loving</label>
    <label><input type="checkbox" name="personality"> Lazy</label>
    <label><input type="checkbox" name="personality"> Crazy</label>
    <input type="text" placeholder="cat photo URL" required>
    <button type="submit">Submit</button>
  </form>
</div>

Your browser information:

Your Browser User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.186 Safari/537.36.

Link to the challenge:
https://www.freecodecamp.org/challenges/ditch-custom-css-for-bootstrap

Look at your h2 element. What class(es) does it have?
Look at your first img. What class(es) does it have?