No rounded corners for c-date-picker and c-time-picker in a c-input-group

When using the following code, the control is displayed without a corner radius:

```
<c-input-group>
  <c-date-picker formControlName="startsOnDate" />
</c-input-group>
```

The same is true for a c-time-picker (testet) and maybe c-multi-select (not testet)