Tutorial
The tutorial is a great place to start if you aren’t familiar with the language. It goes over the basic syntax for elements, as well as how to embed Ruby in the document.
Sass Reference
The Sass reference is the most complete documentation for Sass. It contains information on every language feature, all the options, and how to install it as a Rails plugin.
FAQ
If you’re having trouble or have a question, try the FAQ. If you don’t find what you’re looking for there, ask the Sass community.
API Documentation
Finally, if you want to look at the Sass implementation, check out the YARD API documentation. This probably won’t be too useful for most people, but if you’re writing Ruby code to interact with Sass, that’s a good place to look.