Bright background color in dark mode

[timobrembeck]

Describe the Bug

When the OS or the browser is set to dark mode, the boxes and tables are dark, but the background color is bright, leading to eye strain and bad contrast for headings.

Steps to Reproduce

1. Enable dark mode
2. Open Lunes CMS in browser

Expected Behavior

The background should be dark like it used to be

Actual Behavior

The background is very bright

Additional Information