[Change Request]: Apply border radius to modal footer

[castello-capi]

What type of enhancement/feature is this?

Visual Changes to existing UI Components

Description

Problem:
The modal footer currently has no border radius set and no way to configure this through css variables.

Proposed solution:
Update the stylesheet to include a border-radius with a bound css variable

Use Case/Reasoning for enhancement/feature.

Our style guide uses rounded borders on the modal footer and a more elegant way of setting this would be through a css variable than explicit selectors.

Code of Conduct

• I agree to follow this project's Code of Conduct
• I have searched for existing issues and to the best of my knowledge this is not a duplicate
• This is a single enhancement/feature