from PyQt5.QtWidgets import QApplication, QMainWindow app = QApplication([]) window = QMainWindow() window.setStyleSheet("background-color: white;") window.show() app.exec_()
from PySide2.QtWidgets import QApplication, QSpinBox app = QApplication([]) spinbox = QSpinBox() spinbox.setStyleSheet("color: red; font-size: 18pt;") spinbox.show() app.exec_()In the first example, we create a QMainWindow window and use setStyleSheet to set its background color to white. In the second example, we create a QSpinBox widget and change its font color to red and font size to 18pt using setStyleSheet. Overall, QApplication setStyleSheet is a powerful tool that allows developers to customize the appearance and style of their Qt applications.