21. As a user, I want to be able to use the app in my preferred theme mode

[vivitt]

Summary

Currently, the styles applied to the app are defaulting colors to the 'light' mode. We want to allow users to customize app color scheme preferences by adding a 'dark' mode palette and using it in the app's layout when users have set their system or browser preferences to 'dark' mode.

Acceptance criteria

• Dark mode colors are added to the colors options in tailwind.config.js
• Dark mode palette is applied within the app when the user's mode preferences are set to 'dark'

Notes

We should use the Tailwind dark variant to implement this feature. Refer to Tailwind docs for more info.