The @GNOME desktop just crashed. Doesn't happen often. Firefox and Chromium saved my tabs, and Vim saved almost all of my changes, but still ...
I am using the Dark Theme Toggle @GNOME Shell Extension https://extensions.gnome.org/extension/1518/dark-theme-toggle/
Updating your @GNOME Shell Extensions in @firefox from the GNOME web site can be dicey in @debian stable. An update broke Tray Icons, so I replaced with TopIconsFix. Don't update extensions that are not broken. https://extensions.gnome.org/
I speak Vim. Sort of. I probably can order in a Vim-speaking restaurant. https://vim.fandom.com/wiki/Vim_Tips_Wiki