Fixes round corners when there's only one child in the .button-group.
Fixes round corners when there's only one child in the .button-group.

pedrocorreia/Ink,birthdayalex/Ink,birthdayalex/Ink,rcarmo/Ink,pedrocorreia/Ink,pkdevbox/Ink,birthdayalex/Ink,rcarmo/Ink,pedrocorreia/Ink,sapo/Ink,pkdevbox/Ink,sapo/Ink,pkdevbox/Ink,rcarmo/Ink,sapo/Ink