I am unsure if this is a bug, if not, please close this issue.
When using the <Card> component like so:
<Card onClick={onClick} size="large">
<CardHeader>
...
</CardHeader>
<CardBody>
....
</CardBody>
</Card>
The style applied is empty:

The same is valid for sizes small and medium.
I would expect to have standardized sizes for different <Card> variants.