Optimisation
When CSS is heading for production, it takes an extra step through cssnano (http://cssnano.co/). It's a fantastic and modular CSS minifier by the extraordinarily talented Ben Briggs. Highly recommended.
Besides the more obvious minification step that cssnano provides, there are a number of micro-optimisations you can perform on your CSS just by incorporating plugins from the PostCSS eco-system. For example, by consistently ordering your CSS declarations, Gzip can compress the style sheet more effectively. That's not a job I want to do manually but the postcss-sorting (https://github.com/hudochenkov/postcss-sorting) plugin can do it for free. Here's comparison of Gzip file sizes using the various declaration sorting configurations.
To exemplify, I took a large test CSS file, and unsorted once Gzipped it was 37.59 kB. Here are the file sizes of that same file when Gzipped after using the other declaration sorting configurations:
- postcss-sorting: 37.54
- CSSComb...
