add light/dark mode to homepage

[insectengine]

Made the necessary changes to enable dark/light mode on the home page

resolves #1980

[github-actions[bot]]

🎊 PR Preview be5738416fad9349ec3de11f9b20084e7db731ff has been successfully built and deployed to https://quarkus-site-pr-1983-preview.surge.sh

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[holly-cummins]

Sweet!