PGBT is an Orchard theme that aims to provide a set of common markup and styling so other themes can easily inherit from it.
Almost everything is taken from the core and The Theme Machine shape templates and stylesheets (credit goes to the Orchard Team!), refactored, reorganized and enhanced.
See Pretty Good Bootstrap Base Theme
for a Twitter Bootstrap-based theme serving similarly as a base theme.Commercial-grade support for this theme is available through Lombiq Technologies.
You can install the theme from the Orchard Gallery
Please make sure to read the Documentation