Adds minifying css to part of pre-process build step.
Adds minifying css to part of pre-process build step.

tachyons-css/tachyons,fenderdigital/css-utilities,matyikriszta/moonlit-landing-page,cwonrails/tachyons,getfrank/tachyons,fenderdigital/css-utilities,pietgeursen/pietgeursen.github.io,topherauyeung/portfolio,topherauyeung/portfolio,topherauyeung/portfolio