How to style the background of a QTreeWidget?

[Jakob]

I'm trying to style a QTreeWidget which I added to my form through an application-wide stylesheet. From http://doc.qt.io/qt-5/stylesheet-reference.html I was expecting that I could either do

QTreeView {
    background-color: red;
}

/* or */
QTreeWidget {
    background-color: red;
}

None of them work however - how can I change the background color of this widget?

[Jakob]

It turns out the style was overwritten by a style appearing at the end of the stylesheet...... bummer