Consistent Dark Mode Scheme

Created by: SensehacK

Is your feature request related to a problem? Please describe. I love dark mode everything, Describe the solution you'd like Would like to propose a consistent dark mode color scheme / palette across the whole web app. So that some pages would look consistent with the overall color schemes.

Relevant Issues: #1385 (closed) #1416 (closed) #1400 (closed)

Describe alternatives you've considered Dark Reader extension fairly does great job of dark mode, but isn't officially supported on the web.

Additional context We could utilize SASS variables for better scalability in terms of web development in future.