How to Apply stylesheet to QMessageBox?

[sudhansu]

Hi All,
i need to apply background color as gray in messagebox;
i wrote like

QMessagebox msg(this);
msg.setStyleSheet("background-color: gray ; color : gray");

QMessagebox msg(this);
msg.setStyleSheet("background-color: gray ; color : gray");

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But its not working. Can any body help me?