Bootstrap for Vaadin
Integrating Bootstrap CSS with Vaadin (proof-of-concept).
Using the default bootstrap.css as a base, and then using the default Sass compiler to extend Vaadin class names from the Bootstrap class names. The Vaadin Sass compiler throws a bunch of errors from the Bootstrap CSS at the time of writing, so the default compiler should be used instead.
Current progress can be seen here (can be out of date if I forget to update the demo after a commit):