如何自定义QDialogButtonBox按钮的背景色？

QDialogButtonBox *buttonBox = new QDialogButtonBox(Qt::Horizontal, this);

buttonBox->setStyleSheet("background-color: #RRGGBB;");

buttonBox->addButton("OK", QDialogButtonBox::AcceptRole);
buttonBox->addButton("Cancel", QDialogButtonBox::RejectRole);

#include <QDialog>
#include <QDialogButtonBox>
#include <QVBoxLayout>

class MyDialog : public QDialog
{
public:
    MyDialog(QWidget *parent = nullptr) : QDialog(parent)
    {
        QVBoxLayout *layout = new QVBoxLayout(this);

        QDialogButtonBox *buttonBox = new QDialogButtonBox(Qt::Horizontal, this);
        buttonBox->setStyleSheet("background-color: #RRGGBB;");

        buttonBox->addButton("OK", QDialogButtonBox::AcceptRole);
        buttonBox->addButton("Cancel", QDialogButtonBox::RejectRole);

        layout->addWidget(buttonBox);
    }
};