Animated Button with Tooltip (Pure CSS)

<section>
  <div class="center">
    <h4>Normal State</h4>
    <a class="button" href="#0">
      <span>
        <em>Download</em>
        <i class="fa fa-download"></i>
      </span>
    </a>
    <br>
    <br>
    <h4>Hover state</h4>
    <br>
    <br>
    <br>
    <a class="button hover" href="#0">
      <span>
        <em>Download</em>
        <i class="fa fa-download"></i>
      </span>
    </a>
  </div>
</section>