fix(oas31): use transparent bg-color for accordion and expand buttons

[baarde]

Description

Set background-color to transparent for accordion and expand buttons when loading an OAS 3.1 spec.

Motivation and Context

Currently, when loading an OAS 3.1 spec, the default button background color (ButtonFace) is used for accordion and expand buttons.

In Chrome, ButtonFace happens to be very close to the container background color, so the difference is not noticeable. In Safari, however, the issue is quite apparent.

How Has This Been Tested?

• Run npm run lint: No new problems.
• Run npm run lint-styles: No new problems.
• Run npm run test: All tests pass.
• Run npm run dev
  • Open in Safari & Chrome
  • Set spec URL to https://raw.githubusercontent.com/readmeio/oas-examples/main/3.1/json/petstore.json

Screenshots

Before

After

Checklist

My PR contains...

• No code changes (src/ is unmodified: changes to documentation, CI, metadata, etc.)
• Dependency changes (any modification to dependencies in package.json)
• Bug fixes (non-breaking change which fixes an issue)
• Improvements (misc. changes to existing features)
• Features (non-breaking change which adds functionality)

My changes...

• are breaking changes to a public API (config options, System API, major UI change, etc).
• are breaking changes to a private API (Redux, component props, utility functions, etc.).
• are breaking changes to a developer API (npm script behavior changes, new dev system dependencies, etc).
• are not breaking changes.

Documentation

• My changes do not require a change to the project documentation.
• My changes require a change to the project documentation.
• If yes to above: I have updated the documentation accordingly.

Automated tests

• My changes can not or do not need to be tested.
• My changes can and should be tested by unit and/or integration tests.
• If yes to above: I have added tests to cover my changes.
• If yes to above: I have taken care to cover edge cases in my tests.
• All new and existing tests passed.