Idea: ability to pre-parse CSS at build time

[developit]

To elaborate, it would be great to completely avoid the fetching & parsing hit at runtime by creating a module (and/or webpack loader) that could do the rule parsing and return the mapping of available queries as JSON. I'm still noodling on how this might work given people generally produce CSS from some other format (less, sass, etc), but if it's plausible then the resulting benefit of having no runtime parse overhead would be pretty great.