Since Reqs is built with Drupal, the presentation layer is handled with a “theme”; in this case, reqs_theme.
To manage CSS efficiently, we use SASS. The first thing you'll need to do is install it, which we can do with Drumkit:
make sass
To run Sass, you have to be in the theme directory:
cd web/profiles/reqs_distro/themes/reqs_theme
sass sass:css --watch --no-source-map