pyqt5改变窗体颜色

from PyQt5.QtWidgets import QApplication,QWidget
from PyQt5.QtGui import QColor
import sys
from t import Ui_Form

class myform(QWidget,Ui_Form):
    def __init__(self):
        super().__init__()
        self.setupUi(self)
        self.btn.clicked.connect(self.ok)
    def ok(self):
        r=self.spin1.value()
        g=self.spin2.value()
        b=self.spin3.value()
        col=QColor(r,g,b)
        self.setStyleSheet('QWidget{background-color:%s}'%col.name())

if __name__=='__main__':
    app=QApplication(sys.argv)
    w=myform()
    w.show()
    app.exec_()