[Feat]: Add dark mode functionality

[Ankitha2130]

Is there an existing issue for this?

• I have searched the existing issues

Feature Description

Add dark mode functionality to the entire website.
Please assign this issue to me under gssoc-ext, and a suitable level labels.

Use Case

Improve the UI.

Benefits

No response

Priority

High

Agreements

• I agree to follow this project's Code of Conduct
• I'm a GSSoC contributor
• I'm a Hacktoberfest contributor
• I want to work on this issue
• I'm willing to provide further clarification or assistance if needed.

[github-actions]

Thank you for creating this issue! 🎉 Your issue will soon be reviewed by either the PA or a mentor. Please note that Level 1 is temporary and can be changed during the review. In the meantime, please make sure to provide all the necessary details and context. If you have any questions or additional information, feel free to add them here. Your contributions are highly appreciated! 😊

You can also check our CONTRIBUTING.md for guidelines on contributing to this project.