Screenshot:

PYQT model design:

Screenshot of pyqt designer:

*.UI source code:

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>800</width>
    <height>600</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <widget class="QWidget" name="horizontalLayoutWidget">
    <property name="geometry">
     <rect>
      <x>20</x>
      <y>30</y>
      <width>478</width>
      <height>80</height>
     </rect>
    </property>
    <layout class="QHBoxLayout" name="horizontalLayout">
     <item>
      <widget class="QPushButton" name="pushButton_5">
       <property name="minimumSize">
        <size>
         <width>0</width>
         <height>48</height>
        </size>
       </property>
       <property name="text">
        <string>PushButton</string>
       </property>
      </widget>
     </item>
     <item>
      <widget class="QPushButton" name="pushButton_4">
       <property name="minimumSize">
        <size>
         <width>0</width>
         <height>48</height>
        </size>
       </property>
       <property name="text">
        <string>PushButton</string>
       </property>
      </widget>
     </item>
     <item>
      <widget class="QPushButton" name="pushButton_3">
       <property name="minimumSize">
        <size>
         <width>0</width>
         <height>48</height>
        </size>
       </property>
       <property name="text">
        <string>PushButton</string>
       </property>
      </widget>
     </item>
     <item>
      <widget class="QPushButton" name="pushButton_2">
       <property name="minimumSize">
        <size>
         <width>0</width>
         <height>48</height>
        </size>
       </property>
       <property name="text">
        <string>PushButton</string>
       </property>
      </widget>
     </item>
     <item>
      <widget class="QPushButton" name="pushButton">
       <property name="minimumSize">
        <size>
         <width>0</width>
         <height>48</height>
        </size>
       </property>
       <property name="text">
        <string>PushButton</string>
       </property>
      </widget>
     </item>
    </layout>
   </widget>
  </widget>
 </widget>
 <resources/>
 <connections/>
</ui>

*.UI convert to*.py code

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'untitled1.ui'
#
# Created by: PyQt5 UI code generator 5.15.4
#
# WARNING: Any manual changes made to this file will be lost when pyuic5 is
# run again.  Do not edit this file unless you know what you are doing.
import sys

from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtWidgets import QApplication, QMainWindow


StyleSheet = """
/*Here is a general settings, all buttons are valid, but the later can cover this*/
QPushButton {
         border: none; /*Remove the border* /
}
/*
QPushButton#xxx
 or 
#xx
 They all indicate to be specified by the set ObjectName
*/
QPushButton#pushButton {
         background-color: #f44336; /*Background color* /
}
#pushButton:hover {
         background-color: #e57373; /*Background color when the mouse hovers* /
}
 /*Note that Presset must be placed behind the hover, otherwise there is no effect*/
#pushButton:pressed {
         background-color: #FFCDD2; /*Mouse Press the background color when not letting go* /
}
#pushButton_2 {
    background-color: #4caf50;
         border-radius: 5px; /*rounded corner* /
}
#pushButton_2:hover {
    background-color: #81c784;
}
#pushButton_2:pressed {
    background-color: #c8e6c9;
}
#pushButton_3 {
    background-color: #2196f3;
         /*Limited minimum maximum size*/
    min-width: 96px;
    max-width: 96px;
    min-height: 96px;
    max-height: 96px;
         border-radius: 48px; /*circular* /
}
#pushButton_3:hover {
    background-color: #64b5f6;
}
#pushButton_3:pressed {
    background-color: #bbdefb;
}
#pushButton_4 {
    max-height: 48px;
         Border-Top-Right-Radius: 20px; /*The rounded corner in the upper right corner* /
         Border-BOTTOM-Left-Radius: 20px; /*Corporation in the lower left corner* /
    background-color: #ff9800;
}
#pushButton_4:hover {
    background-color: #ffb74d;
}
#pushButton_4:pressed {
    background-color: #ffe0b2;
}
 /*Based on the text content to distinguish the buttons, the same is based on other attributes to distinguish*/
#pushButton_5 {
         color: white; /*text color* /
    background-color: #9c27b0;
}
"""



class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(800, 600)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.horizontalLayoutWidget = QtWidgets.QWidget(self.centralwidget)
        self.horizontalLayoutWidget.setGeometry(QtCore.QRect(0, 0, 401, 80))
        self.horizontalLayoutWidget.setObjectName("horizontalLayoutWidget")
        self.horizontalLayout = QtWidgets.QHBoxLayout(self.horizontalLayoutWidget)
        self.horizontalLayout.setContentsMargins(0, 0, 0, 0)
        self.horizontalLayout.setObjectName("horizontalLayout")
        self.pushButton_5 = QtWidgets.QPushButton(self.horizontalLayoutWidget)
        self.pushButton_5.setMinimumSize(QtCore.QSize(0, 48))
        self.pushButton_5.setObjectName("pushButton_5")
        self.horizontalLayout.addWidget(self.pushButton_5)
        self.pushButton_4 = QtWidgets.QPushButton(self.horizontalLayoutWidget)
        self.pushButton_4.setMinimumSize(QtCore.QSize(0, 48))
        self.pushButton_4.setObjectName("pushButton_4")
        self.horizontalLayout.addWidget(self.pushButton_4)
        self.pushButton_3 = QtWidgets.QPushButton(self.horizontalLayoutWidget)
        self.pushButton_3.setMinimumSize(QtCore.QSize(0, 48))
        self.pushButton_3.setObjectName("pushButton_3")
        self.horizontalLayout.addWidget(self.pushButton_3)
        self.pushButton_2 = QtWidgets.QPushButton(self.horizontalLayoutWidget)
        self.pushButton_2.setMinimumSize(QtCore.QSize(0, 48))
        self.pushButton_2.setObjectName("pushButton_2")
        self.horizontalLayout.addWidget(self.pushButton_2)
        self.pushButton = QtWidgets.QPushButton(self.horizontalLayoutWidget)
        self.pushButton.setMinimumSize(QtCore.QSize(0, 48))
        self.pushButton.setObjectName("pushButton")
        self.horizontalLayout.addWidget(self.pushButton)
        MainWindow.setCentralWidget(self.centralwidget)

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

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.pushButton_5.setText(_translate("MainWindow", "PushButton"))
        self.pushButton_4.setText(_translate("MainWindow", "PushButton"))
        self.pushButton_3.setText(_translate("MainWindow", "PushButton"))
        self.pushButton_2.setText(_translate("MainWindow", "PushButton"))
        self.pushButton.setText(_translate("MainWindow", "PushButton"))


if __name__ == '__main__':
    app = QApplication(sys.argv)
         # Set style binding: bind by ObjectName name
    app.setStyleSheet(StyleSheet)
    MainWindow = QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

This article refers to GitHub:https://github.com/PyQt5/PyQt