See https://github.com/LearnBoost/stylus/issues/993 for a description of Sylus issue.
Given the number of open Stylus issues and the backlog of pull requests, the easiest way to avoid having unwanted noise in future css changesets is to tweak the foobar Stylus files to avoid the issue.
A guess is that the issue will be avoided if the formulas in main_container_width, local_panel_width, content_width_with_panel, and content_width_no_panel are simplified.
A fix requires tweaking the foobar Stylus main.styl file without changing the foobar appearance in browsers (or make it look better), and verifying the generated CSS is the same for both Stylus version 0.29.0 and 0.31.0. If that works, Linux and Windows CSS output will probably be the same, but must be tested.
A workaround is for all developers to use Stylus 0.29.0:
sudo npm uninstall stylus -g sudo npm install email@example.com -g