How to get jumbotron colour to also cover navbar - css

Question

I'm trying to get a picture (below I've tested with a single background color) to cover the navbar aswell as the showcase/jumbotron. However I can't get it to cover both correctly and the navbar is left untouched - even if I create a div that surround the navbar and jumbotron and assign a background picture to this.
Additionally when I try a picture it is stretched in a rather random way across the showcase, how do I get this to cover the elements correctly ?(image size is 1400x693 svg).
<header class="nav-header">
<nav class="navbar navbar-expand-md navbar-light bg-light">
<div class="container">
<span class="navbar-brand"><i>Logo</i></span>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbar-collapse"
aria-controls="navbar-collapse" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="navbar-collapse collapse">
<ul class="nav navbar-nav ml-auto">
<li class="nav-item"><a class="nav-link" href="#">How it works</a></li>
</ul><!--//nav-->
<ul class="nav navbar-nav ml-auto">
<li class="nav-item">
<a class="nav-link" href="#">My Profile</a>
</li>
<li class="nav-item">
<a class="btn btn-outline-success" href="#">Log out</a>
</li>
</ul>
</div>
</div>
</nav><!--//header-->
</header>
<section>
<div class="showcase">
<div class="container">
<div class="jumbotron jumbotron-fluid showcase-content text-white">
<div class="row">
<div class="col-lg-6">
<h2 class="display-4">Some title.</h2>
<p class="lead">Some additional showcase text.</p>
<p>
<a class="btn btn-secondary text-white " href="#">Get Started -></a>
</p>
</div>
<div class="col-lg-6">
<image></image>
</div>
</div>
</div>
</div><!--//container-->
</div>
</section><!--//promo-->
Css
.showcase {
background-color: red;
background-size: cover;
}
.nav-header {
background-color: transparent;
}
.showcase-content {
background-color: transparent;
}
Codepen:
https://codepen.io/anon/pen/vjqvEE

Answer 1

The issue was having bg-light within the navbar which was overriding assigning the colour to the navbar too.