Scaling background image using styleSheet ? or any other way?

[qtpyqt]

I'm trying to resize a background image on a button

btn.setStyleSheet("background-image: url(:/AddButton.png);"
                         "background-repeat: no-repeat;")

btn.setStyleSheet("background-image: url(:/AddButton.png);"
                         "background-repeat: no-repeat;")

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tried it with

background-size: 10px auto;

background-size: 10px auto;

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but pyqt seems to be missing this CSS attribute

Is there any other way of scaling the background image on the button? I need the background image as the icon on the button will be used on top.

any suggestions?