<div class="card mb-2">
                <div class="list-group list-group-flush border-bottom-0">
                    <a href="#menu_tab_layout" class="list-group-item list-group-item-action active" data-bs-toggle="collapse" role="button">布局学习</a>
                </div>
                <div class="list-group list-group-flush collapse show" id="menu_tab_layout" data-bs-parent="#left-menu-box">
                    <a href="#" class="list-group-item list-group-item-action list-group-item-primary">断点</a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-secondary">容器</a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-success">网格(Grid)</a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-danger">列(Columns)</a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-warning">槽(Gutters)</a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-info">实用工具</a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-light">Z-Index</a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-dark">CSS 网格</a>
                </div>
            </div>

            <div class="card mb-2">
                <div class="list-group list-group-flush border-bottom-0">
                    <a href="#menu_tab_component" class="list-group-item list-group-item-action active" data-bs-toggle="collapse" role="button">组件学习</a>
                </div>
                <div class="list-group list-group-flush collapse" id="menu_tab_component" data-bs-parent="#left-menu-box">
                    <a href="#" class="list-group-item list-group-item-action">手风琴(Accordion)</a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-primary">警报</a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-secondary">徽章</a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-success">面包屑</a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-danger">按钮</a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-warning">按钮组</a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-info">卡片</a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-light">轮播</a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-dark">折叠</a>
                </div>
            </div>

            <div class="card">
                <div class="list-group list-group-flush border-bottom-0">
                    <a href="#menu_tab_form" class="list-group-item list-group-item-action active" data-bs-toggle="collapse" role="button">表单学习</a>
                </div>
                <div class="list-group list-group-flush collapse" id="menu_tab_form"  data-bs-parent="#left-menu-box">
                    <a href="#" class="list-group-item list-group-item-action">
                        表单控件
                    </a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-primary">
                        选择控件
                    </a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-secondary">
                        复选框和单选按钮
                    </a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-success">
                        范围控件
                    </a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-danger">
                        输入组控件
                    </a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-warning">
                        浮动标签控件
                    </a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-info">
                        布局控件
                    </a>
                    <a href="#" class="list-group-item list-group-item-action list-group-item-light">
                        验证控件
                    </a>
                </div>
            </div>