Axlefublr

ctrl+shift+i → … → settings →

1. Enable browser chrome and add-on debugging toolboxes
2. Enable remote debugging

Enable toolkit.legacyUserProfileCustomizations.stylesheets in about:config

Navigate to about:support to figure out your profile directory.

Go to it, create directory called chrome.

Axlefublr

Add the ttf of the font you want into ~/.local/share/Anki2/User 1/collection.media.
Rename it so it has the underscore before the name (this ensures "check empty media" doesn't delete it).
Put this in the CSS of the note where you want to use this font:

@font-face {
  font-family: InputMonoGrafted;
  src: url("_InputMono-Regular.ttf");
}

It should be at the bottom; apparently as the absolute last thing in your CSS. \

Axlefublr

Remap keys on the xkb level

1. xev will show you output like this:

KeyRelease event, serial 36, synthetic NO, window 0x3200001,
    root 0x530, subw 0x0, time 4335057, (943,136), root:(943,694),
    state 0x0, keycode 78 (keysym 0xff14, Scroll_Lock), same_screen YES,
    XLookupString gives 0 bytes:
    XFilterEvent returns: False