占位符属性值在哪

[huyang1998]

Challenge Add Placeholder Text to a Text Field has an issue.
User Agent is: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.100 Safari/537.36.
Please describe how to reproduce this issue, and include links to screenshots if possible.

My code:

<link href="https://fonts.gdgdocs.org/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>Click here for <a href="#">cat photos</a>.</p>

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

<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>
<input type="text" placeholder="猫照片URL">