Draw background of custom widget

I want to change the background color of my custom widget depending on the state of some property, but I want the widget to still be stylable using stylesheets. I understand that I should use QStylePainter in paintEvent, but I can't figure out which draw method to use (I must be stupid).

Code:

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void MyWidget::paintEvent(QPaintEvent *)
{
    QStylePainter painter(this);
 
    QStyleOption option;
    option.initFrom(this);
 
    QColor color;
    switch (this->m_someProperty) {
    case 0:
        color = QColor::fromRgb(255, 255, 255);
        break;
    case 1:
        color = QColor::fromRgb(211, 211, 211);
        break;
    }
 
    painter. //What to use here?
}

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Thanks.