border-color of .list-group inside .card doesn't match .card's border-color

Created by: eproxus

In the Bootstrap 4 example where a list group is included in a card (https://v4-alpha.getbootstrap.com/components/card/#content-types) the border color of the card is #E5E5E5 but the border color of the list items is #DDDDDD which makes them stand out from the card.

Operating system: OS X 10.11.5 Browser: Chrome 51.0.2704.84 (64-bit)