Reactjs 如何覆盖自定义 MUI 手风琴的样式(分隔线和折叠图标)

I aim to create a custom MUI accordion which should look like this:

现在，我已经try 使用这些代码 struct 创建这个自定义MUI Accordion(此Accordion还使用了一些自定义搜索框功能和自定义Accordion数据)

手风琴源代码:

import * as React from "react";
import { useState } from "react";
import AccordionMUI from "@mui/material/Accordion";
import AccordionSummary from "@mui/material/AccordionSummary";
import AccordionDetails from "@mui/material/AccordionDetails";
import Typography from "@mui/material/Typography";
import ExpandMoreIcon from "@mui/icons-material/ExpandMore";
import "./globals.css";
import { accordionData } from "./accordionData.js";
import AddCircleIcon from "@mui/icons-material/AddCircle";
import RemoveCircleIcon from "@mui/icons-material/RemoveCircle";


export default function SimpleAccordion() {
  const [search, setSearch] = useState("");
  return (
    <div>
      <input
        onChange={(e) => setSearch(e.target.value)}
        type="text"
        placeholder="Search"
      />

      {accordionData
        .filter((item) => {
          return search.toLowerCase() === ""
            ? item
            : item.sectionTitle.toLowerCase().includes(search);
        })
        .map((item) => (
          <AccordionMUI key={item.id} className="accordionMui">
            <AccordionSummary
              expandIcon={<AddCircleIcon sx={{ color: "#384558" }} />}
              aria-controls="panel1a-content"
              id="panel1a-header"
            >
              <Typography>
                <b>{item.sectionTitle}</b>
              </Typography>
            </AccordionSummary>
            <AccordionDetails>
              <Typography>{item.sectionContent}</Typography>
            </AccordionDetails>
          </AccordionMUI>
        ))}
    </div>
  );
}

CSS样式源代码:

.accordionMui {
  background-color: rgba(242, 242, 242, 0.1);
  box-shadow: none;
  color: #384558;
}

#panel1a-header {
  padding-top: 5%;
  padding-bottom: 5%;
}

完整的工作演示在这里CodeSandbox.

It currently looks like this:

我的问题是，我的手风琴的最后一条分隔线没有显示出来，不像它之前的部分，在它们下面有一条分隔线.我还想覆盖手风琴分隔线的样式并使其更粗.

我还想将折叠图标更改为它们各自的状态(未展开的Accordion将显示AddCircleIcon，展开的Accordion将显示RemoveCircleIcon)，但出现了一个问题，当我使用这个三元条件expanded={expanded === 'panel1'}时显示Cannot find name 'expanded'，就像这个堆栈接受的问题(How to change icon when accordion summary is expanded?)一样.因此，我不确定如何更改基于展开或未展开状态的折叠图标.

我仍然很困惑，也不确定我应该在Accordion API of MUI上使用哪些类，获得一些关于正确定制和覆盖MUI中的手风琴组件的指南将会有很大的帮助，因为我还在学习MUI.

在这个问题上，你的回答确实会对我有很大帮助.非常感谢.