1. One or more computer-readable media comprising computer-executable instructions for generating a digital map comprising map tiles and independently provided tiles of map details, the computer-executable instructions directed to steps comprising: obtaining a map context indicating a geographic region and a zoom level; detecting an override of default mechanisms that specify appropriate ones of the independently provided tiles of map details, the override identifying a custom mechanism for providing identifiers of appropriate ones of the independently provided tiles of map details in response to the map context; providing the map context to the custom mechanism identified by the override; matching the tiles of map details identified by the custom mechanism to corresponding map tiles, with each matched tile of map details and corresponding map tile pair representing an equivalent geographic area; and causing at least some of the matched tiles of map details to be displayed superimposed over at least some of the corresponding map tiles.