Question about .qss files?

Hello

At Marcus's suggestion I was successful in improving my gnuradio displays by using the
"QT Style Sheets (.qss) files.

However I can not (for the life of me) find the setting that brightens and enlarges
the QT menu's select buttons. I can change the color of the selected item (see attached).

This a minor point, but I'd like the selected item to have a brighter and bigger
mark. In the capture, "Average" is selected, but the select button is small and faint.
Does anybody know how to change the color of the selected item and make the button bigger?
It seems linked to all marks can be colored and scaled, but I can't guess the select field name.

thanks

Glen

Style sheet attached, also