Gruvbox Dark Theme for the Slack Sidebar

Copy and paste this into a Slack DM to yourself, and then click the "Switch sidebar theme" that appears

gruvbox dark `#282828,#3c3836,#ebdbb2,#1d2021,#3e313c,#ebdbb2,#689d6a,#fb4934`

See https://github.com/morhetz/gruvbox#dark-mode-1