cc-badge: border color visible in skeleton (dimmed & strong)

[florian-sanders-cc]

Context

With #630 we've decided to go back to using a border instead of an inner box-shadow.
We've added border in dimmed and strong modes as well so that all modes have the same size.

I forgot to override the border also in skeleton mode which means we see the border color.

Solution

Set border color to the same color as the skeleton background.