.join_us_box {
  background: #F5F6F8;
  padding-top: 100px;
  padding-bottom: 100px;
}

.join_us_box .catname_box {
  justify-content: center;
  margin: 0 auto;
  margin-bottom: 60px;
}

.join_us_box .catname_box .catname {
  color: #303133;
}

.join_us_box .catname_box .catname::after {
  left: 50%;
  transform: translateX(-50%);
  -webkit-transform: translateX(-50%);
  -moz-transform: translateX(-50%);
  -ms-transform: translateX(-50%);
  -o-transform: translateX(-50%);
}

.join_list .join_item_title {
  border-radius: 6px 6px 0 0;
  border: 1px solid #EBEEF5;
  background: #FFFFFF url(../images/join_us_down.png) no-repeat center right;
  background-size: 28px;
  background-position-x: 98%;
  display: flex;
  justify-content: space-between;
  height: 88px;
  line-height: 88px;
  padding-left: 30px;
  padding-right: 84px;
  cursor: pointer;
  margin-top: 24px;
}

.join_list .join_item_title.on {
  background: #FFFFFF url(../images/join_us_up.png) no-repeat center right;
  background-size: 28px;
  background-position-x: 98%;
}

.join_list .join_item_title:first-child {
  margin-top: 0;
  /* padding-bottom: 24px; */
}

.join_list .join_item_title>span {
  width: 33%;
}

.join_list .join_item_title .position {
  font-family: AlibabaPuHuiTi-2-65-Medium;
  font-size: 20px;
  font-weight: 500;
  line-height: 88px;
  letter-spacing: 0.57px;
  color: #303133;
}

.join_list .join_item_title .address {
  font-family: AlibabaPuHuiTi-2-55-Regular;
  font-size: 18px;
  font-weight: 400;
  letter-spacing: 0.57px;
  text-align: center;
  color: #303133;
}

.join_list .join_item_title .join_num {
  font-family: AlibabaPuHuiTi-2-55-Regular;
  font-size: 18px;
  font-weight: 400;
  letter-spacing: 0.57px;
  text-align: right;
  color: #303133;
  overflow: hidden;
  text-overflow: ellipsis;
  -webkit-line-clamp: 2;
  display: -webkit-box;
  -webkit-box-orient: vertical;
}

.join_list li.content_box {
  display: none;
  border-left: 1px solid #EBEEF5;
  border-right: 1px solid #EBEEF5;
  border-bottom: 1px solid #EBEEF5;
  padding: 2rem 1.87rem;
  background: #FFFFFF;
}

.join_list .content_box .content {
  font-family: AlibabaPuHuiTi-2-55-Regular;
  font-weight: 400;
  line-height: 22px;
  letter-spacing: 0.57px;
  text-align: left;
  /* color: #909399; */
  color: #303133;
  font-size: 16px;
}

.join_list .content_box .join_btn {
  display: block;
  font-family: AlibabaPuHuiTi-2-55-Regular;
  font-size: 16px;
  font-weight: 400;
  line-height: 48px;
  letter-spacing: 0.45px;
  text-align: center;
  background: #015CAC;
  color: #fff;
  width: 347px;
  height: 48px;
  border-radius: 8px;
  margin-top: 32px;
}

.join_list .content_box .join_btn:hover {
  background: #D32430;
}

<div class="join_us_box" id="jiaruwomen">
    <div class="container">
        <div class="catname_box wow fadeInUp">
            <div class="catname">加入我们</div>
        </div>
        <ul class="join_list wow fadeInUp">
            {cms:arclist id="join_item" channel="25" type="sons" addon="address,experience,content,email" orderby="weigh asc"}
            <li class="join_item_title {if condition='$i eq 1'} on {/if}">
                <span class="position">{$join_item.title}</span>
                <span class="address">工作地点：{$join_item.address}</span>
                <span class="join_num">{$join_item.experience}</span>
            </li>
            <li class="content_box" {if condition='$i eq 1'} style="display: list-item;" {/if}>
                <div class="content">{$join_item.content}</div>
                <a href="mailto:{$join_item.email}" class="join_btn">申请职位发送邮件到{$join_item.email}</a>
            </li>
            {/cms:arclist}
        </ul>
    </div>
</div>

$(".join_list .join_item_title").on("click", function () {
if ($(this).hasClass("on")) {
  $(this).removeClass("on");
  $(this).next().slideUp();
} else {
  $(this)
    .addClass("on")
    .siblings(".join_list .join_item_title")
    .removeClass("on");
  $(this)
    .next()
    .slideToggle(500)
    .siblings(".join_list .content_box")
    .slideUp();
}
});
$(".join_list .join_item_title.on").next().css("display", "block");