Feature: Rounded the corners on the file area

[yaira2]

Resolved / Related Issues

• Made the sidebar transparent
• Updated the brushes
• Rounded the corners on the file area

Validation
How did you test these changes?

• Did you build the app and test your changes?
• Did you check for accessibility? You can use Accessibility Insights for this.
• Did you remove any strings from the en-us resource file?
  • Did you search the solution to see if the string is still being used?
• Did you implement any design changes to an existing feature?
  • Was this change approved?
• Are there any other steps that were used to validate these changes?
  1. Confirm everything looks correct in light/dark mode

Screenshots (optional)
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