Was tearing my hair out over this yesterday and wanted to save anyone else the trouble
There is a problem with WebStyles that you have made into external project items. They function just fine on their own, but an external item cannot be used as a parent for another webStyle. If you do they show fine in the IDE but the compiled project will not honor any of the parent properties.
If you want to subclass a WebStyle it needs to not be an external item at the moment.
but report and demo project