title: Inset box shadow on unordered list not working
body: <p>I'm trying to set an inset box shadow on an unordered list and it doesn't seem to be showing. I have listed the code below and a screenshot of the result.</p>
  
  <p>Any help would be much appreciated!</p>
  
  <pre class="lang-css prettyprint-override"><code>ul {
      width: 100%;
      list-style: none;
      text-align: center;
      margin: 0;
      padding: 0;
      position: relative;
  }
  
  ul:before {
      border-radius: 5px;
      box-shadow: 0 0 0 1px #b7b7b7, 0 0 0 2px #fff, inset 0 0 15px #000;
      position: absolute;
      height: 100%;
      width: 100%;
      content:'';
      left: 0;
      top: 0;
  }
  
  li {
      -moz-box-sizing: border-box;
      -webkit-box-sizing: border-box;
      box-sizing: border-box;
      padding: 19px 1em;
      width: 100%;
      background-color: #fefefe;
      border-bottom: 1px solid #e1e1e1;
      text-align: left;
      position: relative;
  }
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/kn7Ru.png" alt="enter image description here"></p>