An example of using grunt-uncss on a simple multi-page Sass project.
Clone the repository and install necessary dependencies:
$ git clone https://github.com/addyosmani/grunt-uncss-sass-example.git
$ cd grunt-uncss-sass-example
$ npm install && bower install
Run one of the available build tasks.
$ grunt
will build a version of the project without unused CSS removed. By default the stylesheet this produces is ~95KB.
$ grunt build-uncss
will build a version with unused CSS removed. The stylesheet produced by this build is ~13KB.
The initial app was generated using Yeoman's generator-webapp and includes all the necessary tasks for Sass/Compass compilation, watching and optimization.
The most important point worth noting is that grunt-uncss is run at the very end of your build process here, ensuring all preprocessor tasks have had their chance to complete. This works fine for me.
You can run uncss earlier on in the build if you want, but will need to take care of pointing your usemin blocks to the correct final destination of your CSS files, as they will otherwise point to where it expects your Sass files to go. Something like grunt-processhtml can be used here if required.
(C) Addy Osmani 2014, released under an MIT license