u2f-ref-code/u2f-chrome-extension/infobar.html

<html>
  <head>
    <link rel="stylesheet" href="infobar.css" type="text/css" />
    <script src="infobar.js"></script>
  </head>
  <body>
    <span id="msg"></span>
    <button id="deny"></button>
    <button id="approve"></button>
  </body>
</html>