更改 QTableWidget 单元格的颜色

作为一种选择：

from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.Qt import *


class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(400, 400)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.tableWidget = QtWidgets.QTableWidget(self.centralwidget)
        self.tableWidget.setGeometry(QtCore.QRect(0, 0, 400, 400))
        self.tableWidget.setObjectName("tableWidget")
        self.tableWidget.setColumnCount(0)
        self.tableWidget.setRowCount(0)
        MainWindow.setCentralWidget(self.centralwidget)

        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))


class Widget(QWidget):
    def __init__(self, parent=None):
        super().__init__(parent)
       
        self._widget = QWidget() 
        self._widget.setObjectName("_widget")
        self.setStyleSheet("""
            #_widget {background-color: #E3D18A;}
            #_label {color: #DA723C; font-size: 17px;}
        """)
        
        self._label = QLabel(alignment=Qt.AlignCenter)
        self._label.setObjectName("_label")

        lay = QVBoxLayout(self._widget)
        lay.setContentsMargins(0, 0, 0, 0)
        lay.addWidget(self.label)
        
        layout = QHBoxLayout(self)
        layout.setContentsMargins(0, 0, 0, 0)
        layout.addWidget(self._widget)

    @property
    def label(self):
        return self._label
      

class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow):
    def __init__(self):
        super().__init__()
        self.setupUi(self)

        self.tableWidget.setColumnCount(2)
        self.tableWidget.setRowCount(5)
        
        self.dict_widget = {}
        for row in range(self.tableWidget.rowCount()):
            item = QtWidgets.QTableWidgetItem()
            font = QtGui.QFont()
            font.setFamily('Montserrat')
            font.setPointSize(12)
            font.setBold(True)
            font.setWeight(75)
            item.setFont(font)
            item.setText(str(row + 1))

            widget = Widget(self)
            if row == 0:
                widget.setStyleSheet("""
                    #_widget {background-color: #BD9354;}
                    #_label {color: #fff;  font-size: 18px;}
                """)
                
            widget.label.setText(f'{row + 1}')

            self.tableWidget.setCellWidget(row, 0, widget)  
            self.tableWidget.setItem(row, 1, item)
            
            self.dict_widget[row] = widget

        QtCore.QTimer.singleShot(3000, lambda row=3: self.func(row))

    def func(self, row):
        # измменение цвета ячейки
        self.dict_widget[row].setStyleSheet("""
            #_widget {background-color: #BD9354;}
            #_label {color: #fff; font-size: 18px;}
        """)


QSS = '''
QTableWidget {
    qproperty-showGrid: "false";
    padding-left: 50px;
    padding-right: 50px;
    border: 0px solid;        
    gridline-color: #000000;  
}

QTableWidget::item {
    border-top: 2px solid #9370DB;
    border-right: 2px solid #9370DB;
}
QTableWidget::item:selected {
    background: palette(highlight);  
}

QHeaderView::section:vertical { 
    border: 0px;
    border-top: 2px solid #9370DB
}
QHeaderView::section:horizontal { 
    border: 0px;
    border-right: 2px solid #9370DB
}
'''


if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)

    app.setStyleSheet(QSS)                               # +
    
    Window1 = MainWindow()
    Window1.show()
    sys.exit(app.exec_())