notebookbar height

Libreoffice on Linux (Manjaro XFCE) with GTK3.
The default Notebookbar (Tabbed) has large vertical padding above and below icon groups like in the attached screenshot. This doesn’t happen with Contextual or Groupedbar layouts.
This is somewhat more evident.

Any idea how to change this? I have seen screenshots which show much more compact layouts, so I’m wondering if there’s any local setting for this.