1. A method for providing smoothly scaleable map features on interactive digital maps, the method comprising: receiving by one or more general-purpose processors from a server: (i) map data for a map feature, and (ii) style parameters corresponding to a plurality of styles for rendering map features at each of a plurality of zoom levels; selecting from among the received style parameters (i) a first plurality of style parameters, associated with a particular style, for rendering the map feature at a first zoom level, and (ii) a second plurality of style parameters, associated with the particular style, for rendering the map feature at a second zoom level; forming a container defining the particular style at multiple zoom levels by: (i) encoding first style vertex attributes with (a) the first plurality of style parameters for rendering the map feature at the first zoom level, and (b) spatial parameters for the map feature, (ii) encoding second style vertex attributes with (a) the second plurality of style parameters for rendering the map feature at the second zoom level, and (b) spatial parameters for the map feature; and (iii) grouping the first and second style vertex attributes to form the container; passing the container from the one or more general-purpose processors to a graphics processor by providing the container to a vertex shader implemented by the graphics processor; configuring the vertex shader to generate from the container an interpolated set of style parameters for rendering the map feature at a certain zoom level between the first zoom level and the second zoom level by interpolating between the first plurality of style parameters encoded to the first style vertex attributes and the second plurality of style parameters encoded to the second style vertex attributes; and rendering the map feature at the certain zoom level in accordance with the interpolated set of style parameters.