Progress Bar Widget

Thanks for your response, Sean. I thought about rolling my own but after
some minor changes on my side, I got collective.progressbar to work on
localhost. The bummer is I can't get it to run through nginx. When on
localhost, looking at Network in chrome inspector, it loads http://localhost:8080/Plone/@@collective.progressbar-demo
immediately with status 200 and advances the timeline as the demo
progresses. But via nginx is shows status pending until the demo ends
and only then renders the last demo page with status 200. I added the
following to nginx but has no affect:

add_header 'Access-Control-Allow-Origin' '*';
add_header 'X-Frame-Options' '';
add_header Content-Security-Policy "default-src 'self' 'unsafe-inline' 'unsafe-eval'";

Any ideas on how to debug this?

Update: I tested it on Apache and it works so clearly my nginx config is wrong - here are my nginx configs