1. A method comprising: receiving, at one or more computer systems, a first change to a portion of source code written in a cascading style sheet (CSS) preprocessor language; identifying, with one or more processors associated with the one or more computer systems, a partition associated with the first change, the identified partition selected from a plurality of partitions generated from the source code; determining, with the one or more processors associated with the one or more computer systems, whether the identified partition requires processing using a CSS preprocessor; generating, with the one or more processors associated with the one or more computer systems, a first result in response to applying the CSS preprocessor to the identified partition with the first change when the identified partition requires processing using the CSS preprocessor; generating, with the one or more processors associated with the one or more computer systems, a second result in response to applying one or more operations that do not require the CSS preprocessor to the identified partition with the first change when the identified partition does not require processing using the CSS preprocessor; generating, with the one or more processors associated with the one or more computer systems, an instruction to a client device indicating how to apply the one or more operations to obtain the second result when the identified partition does not require processing using the CSS preprocessor; sending, with the one or more processors associated with the one or more computer systems, the first result to the client device when the identified partition requires processing using the CSS preprocessor; and sending, with the one or more processors associated with the one or more computer systems, the second result and the instruction to the client device when the identified partition does not require processing using the CSS preprocessor such that a similar future change within the identified partition can be computed by the client device using the instruction without having to use the CSS preprocessor.