Suddenly I lost the styling on my application served on Heroku. The reason for that was that all the assets (CSS, JavaScript, images) could not be found. The mysterious error:

ActionController::RoutingError (No route matches "/stylesheets/basic.css" with {:method=>:get}):

was indicating that there is some routing problem. Actually it wasn't that exactly. I have added to my application file which I needed for serving it from Pow in my local development environment. The Momoro Hoax provided a solution which was to change slightly the content of the Of course removing from that app and not keeping it in git repository would also solve that problem.