Fix for simple button in grayscale
Fix for simple button in grayscale

zyj1022/bourbon,greyhwndz/bourbon,Nikeshsuwal/bourbon,jamesmenera/bourbon-libsass,san650/bourbon,nickg33/bourbon,craftsmen/bourbon,chriseppstein/bourbon,thoughtbot/bourbon,zyj1022/bourbon,jamadam/bourbon-docs-jp,Jazz-Man/bourbon,mindeavor/bourbon,jamadam/bourbon-docs-jp,cllns/bourbon,chriseppstein/bourbon,jamadam/bourbon-docs-jp,jamadam/bourbon-docs-jp,Jazz-Man/bourbon,greyhwndz/bourbon,mindeavor/bourbon,setie/bourbon,smithdamen/bourbon,setie/bourbon,nagyistoce/sass-bourbon.io,smithdamen/bourbon,nickg33/bourbon,jamesmenera/bourbon-libsass,thoughtbot/bourbon,craftsmen/bourbon,ismarkunc/bourbon,jasonwalkow/bourbon,jasonwalkow/bourbon