Add Tailwind CSS

[the-teacher]

This branch is for checking Tailwind CSS framework
Can be merged into the master branch any time.

Conclustions

1. TW is not so original. I used atomic css approach many years ago. Implementation was different, but the idea was the same.
2. TW has pretty wide ecosystem and it may work pretty well
3. I do not like rails integration, and I do not like having Rails as a full stack framework at all. It is not news.
4. Without good integration with IDE Tailwind is pretty difficult to use. You need to keep in mind not very obvious aliases.
5. I could not make it work perfect with VScode + ERB in minutes. Probably I need more experiments.