Dark mode is a popular trend, giving users a dark version of the site when their OS has a dark theme enabled. The dark background is easier on the eyes, and better usability for many people.
To implement it in the theme, we could add a dark mode theme settings and use those variables in the css with @media (prefers-color-scheme: dark).
https://css-tricks.com/a-complete-guide-to-dark-mode-on-the-web/