Front Page Card Borders Appear Broken

[ghickman]

On the front page, each card's bottom corners aren't rendering correctly:

Found on Chrome 65, macOS 10.13.3

[evildmp]

I thought they were meant to look like that!

[ghickman]

My frontend skills are very rusty these days but I think the problem is the inner element's square corners are hiding the border's lower rounded corners?