Sass makes CSS fun again. Sass is an extension of CSS, adding nested rules,
variables, mixins, selector inheritance, and more. It's translated to
well-formatted, standard CSS using the command line tool or a web-framework
plugin.

Note however, this package was abandoned upstream:

Ruby Sass was the original implementation of Sass, but it reached its end
of life as of 26 March 2019. It’s no longer supported, and any legacy
projects still using Ruby Sass should migrate to Dart Sass.

The replacement SlackBuild is: dart-sass