本示例中，演示了QScrollArea的使用，以及QScrollBar的样式设定，在代码中使用setStyleSheet设置样式，记得要优先设置scrollArea，再设置窗口的样式，不然QScrollBar的样式会不起作用，使用QSS设置没有这个要求。

效果图：

源代码：

import sys
from PyQt5.QtCore import Qt
from PyQt5.QtGui import QGuiApplication
from PyQt5.QtWidgets import QDialog, QApplication, QPushButton, QScrollArea


from PyQt5 import QtCore, QtGui, QtWidgets


class Ui_Form(object):
    def setupUi(self, Form):
        Form.setObjectName("Form")
        Form.resize(644, 488)
        self.verticalLayout = QtWidgets.QVBoxLayout(Form)
        self.verticalLayout.setObjectName("verticalLayout")
        self.scrollArea = QtWidgets.QScrollArea(Form)
        self.scrollArea.setWidgetResizable(True)
        self.scrollArea.setObjectName("scrollArea")
        self.scrollAreaWidgetContents = QtWidgets.QWidget()
        self.scrollAreaWidgetContents.setGeometry(QtCore.QRect(0, 0, 624, 468))
        self.scrollAreaWidgetContents.setObjectName("scrollAreaWidgetContents")
        self.verticalLayout_2 = QtWidgets.QVBoxLayout(self.scrollAreaWidgetContents)
        self.verticalLayout_2.setObjectName("verticalLayout_2")
        self.pushButton = QtWidgets.QPushButton(self.scrollAreaWidgetContents)
        self.pushButton.setObjectName("pushButton")
        self.verticalLayout_2.addWidget(self.pushButton)
        self.scrollArea.setWidget(self.scrollAreaWidgetContents)
        self.verticalLayout.addWidget(self.scrollArea)

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

    def retranslateUi(self, Form):
        _translate = QtCore.QCoreApplication.translate
        Form.setWindowTitle(_translate("Form", "Form"))
        self.pushButton.setText(_translate("Form", "PushButton"))



class DEMO(QDialog, Ui_Form):
    def __init__(self):
        super(DEMO, self).__init__()
        self.setupUi(self)
        self.resize(955, 625)
        for x in range(30):
            self.scrollAreaWidgetContents.layout().addWidget(QPushButton(f'Button{x}'))

        self.scrollAreaWidgetContents.layout().setContentsMargins(2, 2, 2, 2)
        self.scrollArea.setWidgetResizable(True)

        self.scrollArea.setStyleSheet("""
                    QScrollBar:vertical {
                        border: none;
                        background: #E2E2E2;
                        width: 15px;
                        margin: 10px 0;
                    }
                    QScrollBar::handle:vertical {
                        background: blue;
                        min-height: 20px;
                    }
                    QScrollBar::add-line:vertical, QScrollBar::sub-line:vertical
                    {
                        width: 0px;
                        height: 0px;
                    }
                """)

        self.setStyleSheet("""
                #scrollArea {
                    border: none;
                    border-radius: 6px;
                    padding: 4px;
                    background-color: #ffffff;
                }
                #scrollAreaWidgetContents{
                    background-color: rgb(255,255,255,0);
                }
        """)


if __name__ == '__main__':
    QApplication.setAttribute(Qt.AA_EnableHighDpiScaling)
    QApplication.setAttribute(Qt.AA_UseHighDpiPixmaps)
    QGuiApplication.setHighDpiScaleFactorRoundingPolicy(Qt.HighDpiScaleFactorRoundingPolicy.PassThrough)
    app = QApplication(sys.argv)
    main_win = DEMO()
    main_win.show()
    sys.exit(app.exec_())