chore: remove unused background rules in docs
chore: remove unused background rules in docs

zurb/foundation-sites,denisahac/foundation-sites,zurb/foundation,denisahac/foundation-sites,abdullahsalem/foundation-sites,DaSchTour/foundation-sites,abdullahsalem/foundation-sites,zurb/foundation,DaSchTour/foundation-sites,denisahac/foundation-sites,zurb/foundation-sites,zurb/foundation-sites,abdullahsalem/foundation-sites,zurb/foundation