tldr: Neatline makes it possible to create separate themes for individual exhibits, which is useful if you want to host a collection of self-contained Neatline projects on a single site. To get started, fork the exhibit starter theme, which abstracts out the style, layout, and UX of the Project Gemini over Baja California exhibit.
http://scholarslab.org/geospatial-and-temporal/theming-neatline-exhibits/