fixed dropdown menu visibilty on dark mode

[Achyutem]

Visibility issue for multi-select options in Dark mode #449

Title : fixed dropdown menu visibilty on dark mode

Issue No. : #449

Code Stack : Native (HTML, CSS, and JS)

Close #449

Checklist:

• [X] I have mentioned the issue number in my Pull Request.
• [X] I have commented my code, particularly in hard-to-understand areas
• [X] I have updated the preview with fix in this PR.
• [] I have created a helpful and easy to understand README.md
• [] I have updated the Index.html file for my contribution

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[sadanandpai]

Visibility is completely gone @Achyutem

[sadanandpai]

Closing the PR as it is inactive