Hey Bettina, I saw your message on IRC, it came at 7 in the morning for me but I hadn't checked on my computer that early yet
For most of the Jekyll workshops we run through Github, they are hosted in a sub-path on github.
i.e, the html-css tutorial is hosted at http://opentechschool.github.io/html-css-beginners/ so the subpath would be
/html-css-beginners/. Jekyll needs to know about this for it to work correctly on github; it is set here.
The same applies when you use Jekyll locally, it will serve the workshop under that subpath following that setting. So the address you need to visit would be
Alternatively, you can override the setting on the command line locally if you'd like, by using
jekyll serve -w --baseurl '' and that way you could view it just at