History: Using the Less CSS pre-processor with Tiki

Using the Less CSS pre-processor provides some benefits over editing CSS directly, such as using variables (constants), doing math calculations for color values in the code, and so on. For Tiki's CSS files, the arrangement of .less and .css files is similar to that of the Bootstrap files themselves.

Tiki.css

This file was formerly design.css but was renamed as of Tiki 13 to better indicate its purpose, providing CSS rules for page elements and so on that are outside the scope of bootstrap.css. (The underlying lite.css file was removed, also, as the column layout that it enabled has been replaced by the Bootstrap grid.)

Just as Bootstrap has divided its rules into purpose-specific .less files, tiki.css is compiled from separate files that previously were, together, design.css. The rules have been separated into a number of files according to the page area or feature or function that they are related to. At edit/save time, tiki.css is generated by the pre-processor.

References:

http://lesscss.org/ - An overview of Less, how to download and use, examples and more.
http://coding.smashingmagazine.com/2013/03/12/customizing-bootstrap/ - Customizing Bootstrap
http://jeffcroft.com/blog/2012/feb/23/many-ways-to-use-css-preprocessors/ - The many ways to work with CSS preprocessors [See the comments also.]