[Overlay] Use CultureInfo.InvariantCulture for background-color and z-index

[MarvinKlein1508]

Pull Request

📖 Description

This PR adds CultureInfo.InvariantCulture for the background-color and z-index css styles in FluentOverlay. This saves unnceccsary replacements for , with .

✅ Checklist

General

• I have added tests for my changes.
• I have tested my changes.
• I have updated the project documentation to reflect my changes.
• I have read the CONTRIBUTING documentation and followed the standards for this project.

Component-specific

• I have added a new component
• I have added Unit Tests for my new component
• I have modified an existing component
• I have validated the Unit Tests for an existing component

⏭ Next Steps