One of the design goals with GL was to support cascading styles, so you can start with the predefined world map and just provide deltas of the things you want t

One of the design goals with GL was to support cascading styles, so you can start with the predefined world map and just provide deltas of the things you want to change. For example: "Hide the buildings, set the text font to X, swap the stacking order of layers A and B, and override the default park color to blue".