动态追加固定内容时的车身自动高度

$("#add").on('click',function(){
    count=$('#content > li').length;
    no=count+1;
    data = '<li class="nav-item"><a class="nav-link">Item '+no+'</a></li>';
    $('#add').before(data);
    no++;
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" rel="stylesheet"/>
<div class="wrapper">
<div class="content-wrapper">
<div class="content">
<div class="container-fluid">
<div class="container" style="margin-top:20px; margin-bottom:20px;">
<div class="row">

<div class="col-md-3">
<div class="card">
<div class="card-header">
<h6 class="card-title">Sidebar not fixed column</h6>
</div>
<div class="card-body">
<ul class="nav nav-pills flex-column">
<li class="nav-item"><a class="nav-link">Item 1</a></li>
<li class="nav-item"><a class="nav-link">Item 2</a></li>
<li class="nav-item"><a class="nav-link">Item 3</a></li>
<li class="nav-item"><a class="nav-link">Item 4</a></li>
<li class="nav-item"><a class="nav-link">Item 5</a></li>
<li class="nav-item"><a class="nav-link">Item 6</a></li>
<li class="nav-item"><a class="nav-link">Item 7</a></li>
<li class="nav-item"><a class="nav-link">Item 8</a></li>
</ul>
</div>
</div>
</div>

<div class="col-md-8" style="position:fixed; left:29%; width:70%;">
<div class="card">
<div class="card-header">
<h4 class="card-title">Fixed column with dynamic content appended</h4>
</div>
<div class="card-body">
<ul class="nav nav-pills flex-column" id="content">
<li class="nav-item"><a class="nav-link">Item 1</a></li>
<li class="nav-item"><a class="nav-link">Item 2</a></li>
<li class="nav-item"><a class="nav-link">Item 3</a></li>
<li class="nav-item"><a class="nav-link">Item 4</a></li>
<li class="nav-item"><a class="nav-link">Item 5</a></li>
<li class="nav-item"><a class="nav-link">Item 6</a></li>
<li class="nav-item"><a class="nav-link">Item 7</a></li>
<li class="nav-item"><a class="nav-link">Item 8</a></li>
<li class="nav-item"><a class="nav-link">Item 9</a></li>
<li class="nav-item"><a class="nav-link">Item 10</a></li>
<button type="button" class="btn btn-info float-right" id="add">+ Add</button>
</ul>
</div>
</div>
</div>

</div>
</div>
</div>
</div>
</div>
</div>