Because I can never remember how to vertically center a div...

center.css

.outer {
  display: table;
  position: absolute;
  height: 100%;
  width: 100%;
}

.middle {
  display: table-cell;
  vertical-align: middle;
}

.inner {
  margin: 0 auto;
  width: 400px; /* or whatever else you'd like */
}

/*

Shout out to: https://stackoverflow.com/a/6182661 and http://tachyons.io/components/layout/full-screen-centered-title/index.html 

*/

center.html

<div class="outer">
  <div class="middle">
    <div class="inner">
      <h1>The Content</h1>
      <p>Once upon a midnight dreary...</p>
    </div>
  </div>
</div>