@ Nice

I'm glad you're excited about Builder. Know that the current version does not include a style editor of any kind, so as far as style goes, it's similar to Flexx. As noted in my original comment, we are working on a back-end style editor and hope to have one done within a couple weeks or so (if everything goes according to plan), but it doesn't exist currently.

As for the YAML CSS flexible width, I haven't looked at it, but I don't think it would work since the width customization is offered in the back-end editor and is not modifiable via CSS (in order to prevent breaking the layout widths chosen on the back-end).

I've kicked around the idea of being able to support fluid widths for a while, but it's still just a very conceptual idea, and I don't know if or when it would be implemented.