Docs: Better scroll

[louismaximepiton]

Description

Removing :focus.
Removing * and replacing it by more specific selector.
Adding a scroll-margin-bottom.

Motivation & Context

Didn't work on FF.
Performance issue using the universal selector.
Avoid sticking to the very bottom of the page.

Type of changes

• 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

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

Live previews

• https://deploy-preview-38199--twbs-bootstrap.netlify.app/docs/5.3/components/accordion

Related issues

NA