Compress output using Parcel-CSS

[developit]

Inlined styles should be compressed to deduplicate when multiple stylesheet sources are used. We removed this in the refactor because cssnano was too slow, but it looks like parcel-css is 10x faster and could be used.

[kara]

Closing this issue because ownership of Critters has moved to the Nuxt team, who will be maintaining the project going forward. This repo is archived and won't receive any future updates.

If the issue is still relevant, please re-post it to the actively-maintained fork at https://github.com/danielroe/beasties.