You're looking at the Sitemason® Boilerplate Template - a working template (and corresponding website) that demonstrates just a few of the features of Sitemason. There is no theme - this is merely a collection of Sitemason Tools that you can use however you see fit. Add tools, remove pages, edit and experiment with what is here to learn more about Sitemason, or even use it as-is for your own website (though we doubt anyone will really want to do that).
If you're an end user, you can try editing the content, viewing your changes here, and discovering more about how Sitemason works. For more information see the Getting Started with Sitemason section of our support website.
If you're a developer, you can dig into this template's code to see how Sitemason templates are made. For more information, see the Sitemason Developers website.