It's a slightly modified version of the Monokai theme.

That's a great question and something I plan on writing a full blog post about. But, from a high level, here are the projet goals we've been working with:

1. An administration interface must be good looking and easy to use. The interface is not for developers who understand the underlying data model, rather for operations staff who need to do their job and service our customers.

2. Administration of a production application is way more complex than a simple CRUD of database tables. Although editing data is necessary, most of the time operations staff are finding a resource and performing an action on it or looking up historical data.

3. An administration framework must be highly customizable. Active Admin makes it easy to add controller actions, sidebar elements, action buttons, dashboard widgets, custom forms, show screens and hook in to all resources via plugins.

It's very similar. Internally, its taking a different approach, but in the end, the goals of the projects are fairly close.

Active Admin provides similar features, but does so with a DSL instead of implementing classes, as is the case with Django Admin.