colorless-themes generalizes nordless-theme, a minimalist theme inspired by
nofrils[1], an extremely minimalist colorscheme for vim, and nord[2], a
north-bluish color palette.  More precisely, it provides a macro called
`colorless-themes-make' to easily derive new “mostly colorless” themes.

[1]: https://github.com/robertmeta/nofrils
[2]: https://github.com/arcticicestudio/nord