This is the source of 0a.io (version 3.1)
0a.io (v 3.1) uses Jekyll (v 2.4.0) from the github-pages gem.
To run it, simply do
jekyll serve
or (if you are using bundler)
bundler exec jekyll serve
If you are new to Jekyll & have 3 minutes to spare & want to make a customized github page, you would probably find this useful: Jekyll in 3 minutes.
No JavaScript library or framework are used in 0a.io (besides its home page which uses a bit of Angular and with the exceptions of a few articles that rely on some old jQuery widget I wrote).
Here is a link to the source of 0a.io version 2.0 (built on Meteor).