fix background scaling for large and small screens
fix background scaling for large and small screens

application of `background-size: cover` to set background image to scale to size of screen.  applied as distinct rule so that inline background reapplication won't destroy.  (yay cascade)

before: ![before](http://imgur.com/ROrmxoc)

after: ![after](http://imgur.com/KnSx01F)
shadowfiles/startup,dummass2/dummass2.github.io,scalp42/startup,scalp42/startup,dummass2/dummass2.github.io,shadowfiles/startup