Dark Mode: Update syntax file dark

[MewenLeHo]

Description

Introduce new color palette for dark mode.

Motivation & Context

New color palette for dark mode closer to Bootstrap:

Types of change

• New feature (non-breaking change which adds functionality)

Live previews

• https://deploy-preview-2258--boosted.netlify.app/

Checklist

Contribution

• I have read the contributing guidelines

Accessibility

• My change follows accessibility good practices; I have at least run axe

Design

• (na) My change respects the design guidelines defined in Orange Design System
• (na) My change is compatible with a responsive display

Development

• My change follows the developer guide
• (na) I have added JavaScript unit tests to cover my changes
• (na) I have added SCSS unit tests to cover my changes

Documentation

• My change introduces changes to the documentation and/or I have updated the documentation accordingly

Checklist (for Core Team only)

• My change introduces changes to the migration guide
• (na) My new component is well displayed in Storybook
• (na) My new component is compatible with RTL
• (na) Manually run BrowserStack tests
• (na) Manually test browser compatibility with BrowserStack (Chrome >= 60, Firefox >= 60 (+ ESR), Edge, Safari >= 12, iOS Safari, Chrome & Firefox on Android)
• Code review
• Design review
• A11y review

After the merge

• Manually launch Percy tests

[netlify]

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[julien-deramond]

LGTM for a first version. The rendering is already better.
But let's continue to work on it for improvements.