Well your wishes have been fulfilled. Over on GitHub is a page ready designed for you to use!

It's my SEAuthentication repro.

#What does it do?

#How does it work?

The essential code is below. There is a load of CSS to go with it.

<center>
  <p id="token">
      <script>
      window.onload = function() {
        var url = location.href
        var index = url.search(/access_token=/g)
        var access_token = url.substring(index+13,index+37)
        document.getElementById("access-token-c").style.display='none';
        if (index > 18) {
          document.getElementById("token-box").value = access_token;
          
          document.getElementById("access-token-c").style.display = 'block';
        }
      document.getElementById("token-box").select();
      }
    </script>
    <p id="token-description" class="token-title">
      Your access token is:<br>
    </p>
  </p>
  <input id="token-box" type="text" name="token">
  <div id="copy-box" class="token-copy">
    Copy with Ctrl+C
  </div>
</center>