Nest an anchor element

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

  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>

<p> view more <a href="http://www.freecatphotoapp.com">cat photos</a></p>

<img class="smaller-image thick-green-border" src='//cdck-file-uploads-global.s3.dualstack.us-west-2.amazonaws.com/freecodecamp/original/3X/6/1/61a3499c5abb165be990aa0c1abd23342e60c663.jpg' alt="A cute orange cat lying on its <pback. ">

<p class="red-text">Kitty ipsum dolor sit amet, shed everywhere shed everywhere stretching attack your ankles chase the red dot, hairball run catnip eat the grass sniff.</p>
<p class="red-text">Purr jump eat the grass rip the couch scratched sunbathe, shed everywhere rip the couch sleep in the sink fluffy fur catnip scratched.</p>

what is the mistake in the code

Where is the code? And what have you tried?

This is the only mistake I see, and it shouldn’t be impacting anything other than whomever reads the alt attribute with a screen reader:

... alt="A cute orange cat lying on its <pback. ">

Other than that, I’d need to know what you’re trying to achieve (i.e. what you’re expecting the code to do) and what’s happening instead.

Here’s what I see in the browser when I use your code:

EDIT: Also, take a look at this link to learn more about asking questions so you can get the answers you need: https://medium.com/@gordon_zhu/how-to-be-great-at-asking-questions-e37be04d0603

Hi,
You need head and body tags. You should put link and style tags inside the head tag and the rest of the markup inside the body tag.