🎨  Make blog icon backround transparent (#628)
🎨  Make blog icon backround transparent (#628)

refs TryGhost/Ghost#7688
acburdine/Ghost-Admin,JohnONolan/Ghost-Admin,TryGhost/Ghost-Admin,kevinansfield/Ghost-Admin,TryGhost/Ghost-Admin,kevinansfield/Ghost-Admin,JohnONolan/Ghost-Admin,acburdine/Ghost-Admin