Solution mentioned by Chris Baswell at https://stackoverflow.com/a/
45969088
### Button group
- Rewrote component with flexbox.
-- Removed `.btn-group-justified`.
+- Removed `.btn-group-justified`. As a replacement you can use `<div class="btn-group d-flex" role="group"></div>` as a wrapper around elements with `.w-100`.
- Dropped the `.btn-group-xs` class entirely given removal of `.btn-xs`.
- Removed explicit spacing between button groups in button toolbars; use margin utilities now.
- Improved documentation for use with other components.