Python 设置样式表时，QTableView会忽略数据

我有一个

QTableView

，我想设计它的项目边距，并根据它的型号值给它不同的颜色。但是，一旦我设置了样式表，它就会忽略角色的数据，如

Qt.BackgroundRole

。我的问题是：如何设置动态背景着色的边距。这是我的mwe：

#!/usr/bin/env python3

import sys

from PyQt5.QtWidgets import QTableView, QApplication
from PyQt5.QtCore import QAbstractTableModel, Qt, QTimer
from PyQt5.QtGui import QBrush


class Model(QAbstractTableModel):
    counter = 0
    COLORS = [QBrush(Qt.green), QBrush(Qt.red), QBrush(Qt.blue), QBrush(Qt.cyan)]

    def rowCount(self, *_):
        return 2

    def columnCount(self, *_):
        return 2

    def data(self, index, role):
        if role == Qt.DisplayRole:
            return f'{index.row()} - {index.column()} - {self.counter}'
        elif role == Qt.BackgroundRole:
            ind = (index.row() + index.column() * 2 + self.counter) % 4
            return self.COLORS[ind]

    def change(self):
        self.counter += 1
        self.dataChanged.emit(self.index(0, 0), self.index(2, 2))


# Setup
app = QApplication(sys.argv)
model = Model()
view = QTableView()
view.setModel(model)
view.show()

# This is the line that causes the headache, I want to define some margins,
# however once setting this stylesheet it ignores my data calls with
# role == Qt.BackgroundRole
if True:
    app.setStyleSheet('''
        QTableView::item {
            background-color: grey;
            margin-top: 5px;
            margin-bottom: 5px;
            min-height: 20px;
        }''')


# The timer simulates new data comming in. We want to color each cell according
# to the status of its value.
timer = QTimer()
timer.timeout.connect(model.change)
timer.start(500)
app.lastWindowClosed.connect(timer.stop)

sys.exit(app.exec_())

设置样式表时

不设置样式表时