No rounded corner for Button addons with c-form-feedback

[bernik1980]

If you use a Button addon inside a c-input-group, which has a c-form-feedback too, the corners of the button are not rounded anymore.

Button is square:

<c-input-group>
  <select cSelect>
  </select>

  <a cButton color="secondary" variant="outline">dummy</a>

  <c-form-feedback [valid]="false">dummy</c-form-feedback>
</c-input-group>

Button has rounded corners:

<c-input-group>
  <select cSelect>
  </select>

  <a cButton color="secondary" variant="outline">dummy</a>
</c-input-group>