fix(docs-ui): improve responsive layout for prev/next navigation cards

[kams05-ops]

What has changed?

This PR improves the styling and mobile responsiveness of the Previous / Next navigation cards in the docs.

• Fixed layout issues on smaller screens by stacking cards vertically
• Improved spacing and padding for better readability
• Adjusted font sizes for titles and labels on mobile
• Refined border, hover, and visual styles for a cleaner UI
• Ensured styles work properly in both light and dark themes

This PR Resolves #3657

Type of change

Ui enhancement.

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue).
• [-] New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).
• Documentation update (if none of the other choices apply).

How Has This Been Tested?

npm run start

Tested locally on multiple screen sizes using browser responsive tools.
Verified layout, spacing, and typography in both light and dark modes across several docs pages.

Checklist:

• [-] My code follows the style guidelines of this project.
• [-] I have performed a self-review of my own code.

[Achanandhi-M]

LGTM