This is a Vim's color scheme plugin: "monochromenote".
monochromenote is inspired by KOKUYO's awesome notebook. See below for details.
To enable monochromenote, install this plugin and run this command.
colorscheme monochromenote
colors/monochromenote.vim is generated by code. See koron/csvim:cmd/monochromenote/monochromenote.go for details.