As a Drupal themer, we're often tasked with building multiple sites concurrently. One site may be a new build from scratch, and another could be a site built two years ago that is getting a new feature. If they utilize Sass in the theme, then they both have one thing in common:

They have Ruby gem dependencies.

What are they chances that both sites use the same versions of the same gems? Slim? None? Ever tried to build a set of Sass files when you don't have the correct gem versions installed? Oh what a pain.

Let's take the pain away with a few simple techniques.

Ruby and RVM

OS X comes with Ruby built-in, but I highly recommend installing Ruby with RVM. With RVM, you can specify the version of Ruby you want installed, plus a whole lot more. Installation instructions are available, but are outside the scope of this blog post.