def METHOD_NAME(app):
    """
    Apply application-wide style-sheet rules.
    """
    styleSheetText = (Path(__file__).parent / "ilastik-style.qss").read_text()
    # Adding style sheet for QSlider fixes an osx-specific issue: updating the
    # handle programmatically via slider.setValue is not reflected in the UI once
    # the slider has been moved manually.
    # This behavior is gone after setting the style sheet.
    # link to Qt issue: https://bugreports.qt.io/browse/QTBUG-96522
    # ilastik issue: https://github.com/ilastik/ilastik/issues/2623
    if platform.system() == "Darwin":
        styleSheetText += (Path(__file__).parent / "ilastik-style-osx.qss").read_text()
    app.setStyleSheet(styleSheetText)