TYPO3 Core

:) Should be "btn btn-secondary" haha

Did you try this?

- { name: "Button: Sekundär", element: "a", classes: ['btn', 'btn-primary'] }

Wittkiel Gruppe wrote in #note-3:

Did you try this?
[...]

Thanks, tested with anchors and it works :)
Still got the problem to set a individual class to lists and tables.
Not sure if this is a generally problem in CKEditor 5...

Samuel Heinz wrote in #note-4:

Still got the problem to set a individual class to lists and tables.
Not sure if this is a generally problem in CKEditor 5...

This is also a huge problem for us, especially tables. It's sadly a general problem with CKEditor 5, see for example #99681 and #99669 and https://github.com/ckeditor/ckeditor5/issues/11577 and https://github.com/ckeditor/ckeditor5/issues/13208 ..