Non breaking spaces not respected at page break
If a page break occurs within a group like
« word » (french guillemets need non-breaking spaces, or better, narrow non-breaking spaces:
« word »), the starting guillemet can be isolated at the end of the page.
How should it work
The group shouldn’t be broken, and be switched to the next page.
Non breaking spaces variations: https://en.wikipedia.org/wiki/Non-breaking_space#Width_variation