GitHub pages maybe deployed by nginx.
Just simply create an "index.html", add any content you want, push to a repo named like "static-web", get into settings of the repo, turn it into github pages, select origin master being the static resources.
And you can see your content of index.html in this site:
https://github.com/zecoo/static-web
[change "zecoo" to your own id]
js, css and img are all supported by github pages. Enjoy it.