Kindly asked Claude to work a custom Nix configuration for a browser instance designed only for paogarden. For now, I don't need much:

• no address bar;
• Dark Reader and Vimium;
• custom zoom level.

A few CSS tricks make Firefox more palatable to the heavy Vimium user:

#nav-bar {
  visibility: collapse !important;
}

#TabsToolbar {
  visibility: collapse !important;
}

#titlebar {
  visibility: collapse !important;
}

Then, by navigating to about:config and setting toolkit.legacyUserProfileCustomizations.stylesheets to true, the URL bar disappears, which is great!

There is still a problem to solve with Vimium and CodeMirror; pressing Esc or ctrl+] will not return the green CodeMirror cursor; only ctrl+c seems to work reliably, which is a bit of a bummer — I'd prefer not to promote different escaping habits across my applications. But this is nevertheless a good compromise for now!