Add details to at-breakpoint font-size argument documentation
Add details to at-breakpoint font-size argument documentation

gonsakon/susy,BionicClick/susy,briangonzalez/susy,kraftner/susy,katoffsky/susy,pairyo/susy,MichaelArestad/susy,gastonfig/susy,kraftner/susy,acdlite/susy,rajkaushik05/susy,oddbird/susy,greyhwndz/susy,justnorris/susy,lencioni/susy,gabskoro/susy,rainforestapp/susy,essdot/susy,rainforestapp/susy,kaij/susy,justnorris/susy,briangonzalez/susy,oddbird/susy,Sapphire64/susy,gonsakon/susy,Sapphire64/susy,pairyo/susy,greyhwndz/susy,leopic/susy,ericam/susy,kaij/susy,webdev1001/susy,webdev1001/susy,kaij/susy,tsi/susy,gabskoro/susy,BionicClick/susy,pairyo/susy,rainforestapp/susy,ericam/susy,MichaelArestad/susy,rajkaushik05/susy,lencioni/susy,katoffsky/susy,rajkaushik05/susy,gastonfig/susy,katoffsky/susy,acdlite/susy,greyhwndz/susy,Sapphire64/susy,leopic/susy,kraftner/susy,tsi/susy,essdot/susy,ericam/susy,BionicClick/susy,gabskoro/susy