Feature request: Add additional dark colors

[argyleink]

The current set of colors is great but it does leave me needing to write my own "very dark saturated" colors. Would love it if there were 2-3 more colors available that were darker.

Just like how there's a healthy set of light colors (0-3), I'd love to see some similar but in the dark range.

These come in handy for dark mode

[argyleink]

https://github.com/fchristant/colar has an article about adding extra dark colors and a repo with their choices