PostCSS?

[deansallinen]

Might be good to add PostCSS for svelte-preprocess. Some possible benefits:

1. Autoprefixer for vendor prefixes
2. CSSnext to use new CSS syntax instead of SASS
3. PreCSS can replace any remaining need for SASS
4. StyleLint could help with consistency
5. CSSNano for minification and optimization in production
6. Font Magician might help with typography stack