A similar bug was filed 12 years ago with the same request, but it was rejected because QSS was not fully functional or well documented at the time. That isn't the case today though. This feature would be amazing because it would provide an easy way to create themes, and it would likely be implemented by LXQt and any future Qt desktop environments as well. This would also probably be very easy to implement (I don't mean to be rude). Please consider it. Thanks! --- 2010 bug (I don't know why it's crossed over) --- https://bugs.kde.org/show_bug.cgi?id=164955 --- 2010 forum thread discussing the feature. 44 likes and 0 dislikes --- https://forum.kde.org/viewtopic.php?f=90&t=88098
UPDATE: LXQt already supports this. All the more reason KDE should as well.
Let's see how the email thread you started pans out. *** This bug has been marked as a duplicate of bug 164955 ***