<!DOCTYPE html>
<html>
  <head>
    <title>Install Page Shot</title>
    <style type="text/css">
html {
  font-family: sans-serif;
}
    </style>
  </head>
  <body>
    <center>
      <img src="/static/img/pageshot.svg" height="256" width="256" />
      <h1>Page Shot</h1>
      <a href="https://testpilot.firefox.com/files/pageshot/pageshot-0.1.201608231911.xpi">Install</a>
  </body>
</html>

<!DOCTYPE html>
<html>
  <head>
    <title>Install Page Shot</title>
    <style type="text/css">
      html {
        font-family: sans-serif;
      }
    </style>
  </head>
  <body>
    <center>
      <img src="/static/img/pageshot.svg" height="256" width="256" />
      <h1>Page Shot</h1>
      <a href="https://testpilot.firefox.com/files/pageshot/pageshot-0.1.201608231911.xpi">Install</a>
    </center>
  </body>
</html>

Add missing closing center tag
Add missing closing center tag
