Sass is a great way to make your .css in a more structured way that is easier to maintain. The upstrean version is made in Ruby, but here is many other versions written in other languages. I want to use libsass writen in C++ and the python-libsass python bindings there can be run from a commandline. I like to keep the requirements for my projects down, and Ruby or Node need a lot of packages to make Sass work and I need something that can be used for creating .css for Gtk applications, that can be build into packages and Node & Ruby will add a lot of unneeded requirement just to use Sass for non-web applications.