How to style a QWizard’s button area ?

Style the QWizard’s button area:

To fixed the medium  style to ClassicStyle then QWidgets are applicable  for QSS.

wizard->setWizardStyle(QWizard::ClassicStyle);

The  VistaStyle painting  the hardcoded  source of QWizard   as:

if (wizardPrivate->isVistaThemeEnabled(QVistaHelper::VistaBasic)) {
    if (window()->isActiveWindow())
        painter.setPen(QPen(QBrush(QColor(169, 191, 214)), 0)); // ### hardcoded for now
    else
        painter.setPen(QPen(QBrush(QColor(182, 193, 204)), 0)); // ### hardcoded for now
    painter.drawLine(0, 0, width(), 0);
}