By adding the following snippet to a project's view...
<script src="https://widget.glitch.me/widget.min.js"></script>
...this project's style.css will be added to the header, and the remix button and view source link will be appended to any element with id="gWidget".
For example, this project's index view in views/index.html shows an empty footer element...
<footer id="gWidget"></footer>
On page load, the remix button and view source link will appear there!
This same documentation can be found at
https://widget.glitch.me
\ ゜o゜)ノ