title: How to vertically center a div on page?
body: <p>How can I center the #box div vertically centered on the page? I tried vertical-align: middle; but it doesn't work. You can check the site live <a href="http://hentaidoujinshi.com/8" rel="nofollow noreferrer">here</a></p>
  
  <p>This is the css:</p>
  
  <pre><code>iframe {
    position: fixed;  
    width: 100vw; 
    height: 100vh;  
    border: none; 
    margin: 0; 
    padding: 0; 
    overflow: hidden; 
    z-index: 999999;
  }
  
  body {
    background-color: #000;
  }
  
  #box {
    text-align: center;
    vertical-align: middle;
  }
  
  #link {
    color: #FFF;
  }
  
  #download {
    color: #FFF;
  }
  </code></pre>