[BUG] Dark mode on About page

[Bushra-gh]

Describe the bug
Dark mode not working Properly on About page

Expected behavior
On clicking the mode change button , it doesn't show dark mode completely , the background is still light , only the navbar changes to black.

[github-actions]

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Meanwhile make sure you've visited the README.md, CONTRIBUTING.md, and CODE_OF_CONDUCT.md before creating a PR for this. Also, please do NOT create a PR until this issue has been assigned to you. 😊