Fix rounded borders for nested cards within card in card-group

[mscdex]

Description

This fixes an issue where borders are not rounded for cards nested within a card in a card group.

Motivation & Context

This fixes an issue where borders are not rounded for cards nested within a card in a card group.

Type of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Refactoring (non-breaking change)
• [ ] Breaking change (fix or feature that would change existing functionality)

Checklist

• [x] I have read the contributing guidelines
• [x] My code follows the code style of the project (using npm run lint)
• [ ] My change introduces changes to the documentation
• [ ] I have updated the documentation accordingly
• [ ] I have added tests to cover my changes
• [ ] All new and existing tests passed

Live previews

Related issues

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I have no idea if this would be considered a breaking change or not. Personally I can't imagine someone relying on the previous greedy selector behavior, but anything is possible I suppose.

[mdo]

What does this fix, is there a demo of a bug or an associated issue?

[mscdex]

Here's a demo: https://jsfiddle.net/1r7mjdzb/1/

If you look at the "Nested Card 1" header, the upper-right border is not rounded as expected. Similarly, if you look at the "Nested Card 2" header, the upper-left border is not rounded as expected.

It's the same deal for the respective footers but the lower-right and lower-left borders respectively.

[mdo]

Thanks! Yeah I don't think I anticipated folks nesting cards like this, but I should always expect the unexpected with Bootstrap at this point lol. That makes sense and hopefully won't be a huge issue for others.\

/cc @julien-deramond for thoughts