Unrecognized class
Keystone knows every class it can handle — the handler classes, your shortcuts, and a short list of Pandoc-native ones. A class that matches none of them is almost always a typo, so Keystone names it and suggests the nearest real one.
What it looks like
::: {.vspcae size="medium"}
:::
WARN: unrecognized class 'vspcae' (in .vspcae)
It is not a handler, shortcut, or Pandoc-native class.
Did you mean 'vspace'?
See https://keystone.knight-owl.dev/errors/unrecognized-class/
What it means
The class vocabulary is closed — there is no author CSS channel, so a class that resolves to nothing can only be a mistake. This is a warning, not an error: the element still builds, so the bogus class leaks into your book unstyled. Under strict mode it becomes fatal, which is why a strict build before publishing is worth the habit.
Take the suggestion, or check the spelling
Where the suggestion names what you intended, that is the fix. Otherwise
check the spelling against the
system shortcut reference and your own
shortcuts.yaml. A class that is genuinely yours needs a
shortcut or handler defining it —
Keystone won't style a class it doesn't know.
Related
- Unrecognized attribute — the same idea, one level down: a recognized class carrying a name it doesn't accept.