Update themes.scss for bg color change to #010100 in dark mode

Ticket(s) / Related Merge Requests

Summary of Changes

Change dark mode primary background color to #010100, which has deeper contrast and looks more stark (in line with Twitter's lights out mode)

Side by side comparison

Sandbox example

Current Minds app

Change primary background dark from #1C1D1F to #010100

Testing Considerations

Deployment Considerations

Regression Scope

Platform Affected (web, mobile, etc)

Web (need to create a mobile ticket)

Developer Testing Completed

Screenshots / Screen Recording

Does this impact

• Localization
• Dark/light mode
• Guest mode

Definition of Done Checklist

• The Acceptance Criteria has been met
• Code is tested: Testing includes unit/spec, E2E/automated and manual testing
• Merge requests description has been filled out