Explain how class attribute is functioning in this program

Tell us what’s happening:
i am inserting border-radius within .thick-green-border attribute then the border is turning into blue color for no reason and when I am putting radius attribute within .smaller-image attribute then border is getting curved as expected but I think image should get curved instead of border. please explain me how this class attribute is functioning

Your code so far


<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;
}

.smaller-image {
  width: 100px;
  border-radius: 10px
}
</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>
  <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>

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.135 Safari/537.36.

Challenge: Add Rounded Corners with border-radius

Link to the challenge:

As for the border-radius, both the smaller-image and thick-green-border classes are applied to the img tag, so when you add a border radius, the green border appears to have a radius instead of the image. Try removing the thick-green-border class from the image to see the effect of border-radius on the image without the green border.