Top navbar to go underneath side navbar - html

Question

I'm currently using the example from bootstrap called 'dashboard' I'm wanting to get the top navbar to actually tuck underneath the side navbar. Like this example: Image Example from Dribbble
I've put the dashboard code from bootstrap onto jsfiddle for ease of use for those that are willing to help (I really appreciate any help with this).
https://jsfiddle.net/1dy65wqx/
It should impact this:
<nav class="navbar navbar-expand-md navbar-dark fixed-top bg-dark">
<a class="navbar-brand" href="#">Dashboard</a>
<button class="navbar-toggler d-lg-none" type="button" data-toggle="collapse" data-target="#navbarsExampleDefault" aria-controls="navbarsExampleDefault" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarsExampleDefault">
<ul class="navbar-nav mr-auto">
<li class="nav-item active">
<a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Settings</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Profile</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Help</a>
</li>
</ul>
<form class="form-inline mt-2 mt-md-0">
<input class="form-control mr-sm-2" type="text" placeholder="Search" aria-label="Search">
<button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
</form>
</div>
</nav>
</header>
<div class="container-fluid">
<div class="row">
<nav class="col-sm-3 col-md-2 d-none d-sm-block bg-light sidebar">
<ul class="nav nav-pills flex-column">
<li class="nav-item">
<a class="nav-link active" href="#">Overview <span class="sr-only">(current)</span></a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Reports</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Analytics</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Export</a>
</li>
</ul>
<ul class="nav nav-pills flex-column">
<li class="nav-item">
<a class="nav-link" href="#">Nav item</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Nav item again</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">One more nav</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Another nav item</a>
</li>
</ul>
<ul class="nav nav-pills flex-column">
<li class="nav-item">
<a class="nav-link" href="#">Nav item again</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">One more nav</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Another nav item</a>
</li>
</ul>
</nav>

Answer 1

I have changed few styles, please add this to your css file..
<div class="row" style="position:relative;">
<nav class="col-sm-3 col-md-2 d-none d-sm-block bg-light sidebar" style="position:fixed; z-index:2000; top:0px;">