I've been using sass and compass on this computer for a few months with no issues.
Additionally, my config.rb and sass directories have always been set up the same way, and they're the same on all of my projects.
Recently, I started getting this error in Sublime when I build the sass:
Sass::SyntaxError: File to import not found or unreadable: compass.
error sass/style.scss (Line 36 of _vertical_rhythm.scss: Incompatible units: 'px' and 'em'.)
After a month of troubleshooting, the solution ended up being simpler than expected.
I uninstalled all versions of both Sass and Compass, and then I installed the latest Compass and let it install Sass automatically.
So after doing
sudo gem uninstall compass and
sudo gem uninstall sass, I did
sudo gem install compass. That installed both Compass and its dependencies (Sass version 3.2.19). (I'm on a Mac, so I had to use