When you will feel like it and if you plan to do more work on Styling FreeCAD please open a thread in one of the mentioned forum sections. Something like Dark and Light FreeCAD stylesheets (v3.x WIP) ... We can therefore talk about it there.
As for the stylesheets merged into master it would be great if you would add that nicely styled check boxes to QListWidget items (QListWidgetItem) if possible. I noticed the ones in TabBar are done in system default style and after i checked where they could be found in FreeCAD. One example is Part WB -> Fillet tool. Select some edges to fillet and you can observe them.