Apply improved styling based on UX feedback
Apply improved styling based on UX feedback

- Only apply extra margins and borders between checkbox components
- Change cursor to `not-allowed` when checkbox is disabled
- Adjust handling of inline checkbox styling vs block

mmkassem/gitlabhq,stoplightio/gitlabhq,mmkassem/gitlabhq,mmkassem/gitlabhq,mmkassem/gitlabhq,stoplightio/gitlabhq,stoplightio/gitlabhq,stoplightio/gitlabhq