From the accompanying blog post: "Here at ZURB, we believe that everything we do has to consider the mobile experience."

You might want to consider making the project page responsive.

Also, the tweet box is way off to the side, I had to resize my window to fully see it.

http://www.zurb.com/playground serves a separate mobile optimized page, but the link to the responsive email templates points to http://www.zurb.com/responsive-email-templates, which doesn't exist.