如何动态设置QProgressBar样式表？

from PyQt5.QtWidgets import QApplication, QProgressBar, QVBoxLayout, QPushButton, QWidget

class ProgressBarDemo(QWidget):
    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):
        self.progress = QProgressBar(self)
        self.btnChangeStyle = QPushButton('Change Style', self)
        self.btnChangeStyle.clicked.connect(self.changeStyle)

        vbox = QVBoxLayout()
        vbox.addWidget(self.progress)
        vbox.addWidget(self.btnChangeStyle)

        self.setLayout(vbox)
        self.setWindowTitle('Dynamic QProgressBar Styling')

    def changeStyle(self):
        # 动态改变样式表
        new_style = """
            QProgressBar {
                border: 2px solid grey;
                border-radius: 5px;
                text-align: center;
            }
            QProgressBar::chunk {
                background-color: #05B8CC;
                width: 10px;
                margin: 0.5px;
            }
        """
        self.progress.setStyleSheet(new_style)

if __name__ == '__main__':
    app = QApplication([])
    demo = ProgressBarDemo()
    demo.show()
    app.exec_()