Prevent NavBar from Expanding When Using Z-Index - css

Question

I posted a previous question concerning Positioning NavBar at Top of Page but Losing Clickability on Main Content. The question was answered but it has now led to an unintended consequence. At first it prevented a dropdown menu item from appearing above the content. I updated the dropdown with a z-index: 99999; position: relative; value to get it to display above the content but now it expands the height of the Header section. Here are 3 images.
Unselected Dropdown:
How it used to appear:
How it now appears using z-index: 99999;position: relative;
Here is the code for the navbar:
<header>
<div class="navbar navbar-inverse" id="edadTopNavigation">
<div class="container-fluid app-navbar">
<div class="navbar-collapse collapse app-navbar-text-section">
<ul class="nav navbar-nav">
<li class="nav-item dropdown">
<a class="nav-link text-dark" asp-area="" asp-controller="Home" asp-action="Index">Home</a>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" id="adminDropdownMenuLink" href='#' data-toggle="dropdown" aria-haspopup="true" aria-expanded="false"><div class="fa fa-cog"></div> Admin</a>
<div class="dropdown-menu" aria-labelledby="adminDropdownMenuLink">
<div>
<a class="nav-link text-dark" asp-area="" asp-controller="Acronym" asp-action="Index">Acronyms</a>
</div>
<div>
<a class="nav-link text-dark" asp-area="" asp-controller="User" asp-action="Index">Users</a>
</div>
<div>
<a class="nav-link text-dark" asp-area="" asp-controller="User" asp-action="Index">States</a>
</div>
<div>
<a class="nav-link text-dark" asp-area="" asp-controller="User" asp-action="Index">Countries</a>
</div>
</div>
</li>
</ul>
</div>
</div>
</div>
</header>
Here is the current CSS:
.navbar {
/* margin-bottom: 0px;*/
position: fixed; /* Set the navbar to fixed position */
top: 0; /* Position the navbar at the top of the page */
width: 100%;
overflow: hidden;
z-index: 200
}
.dropdown-menu {
padding: 10px;
background-color: #fff;
background-color: #fffff2;
z-index: 99999;
position: relative;
}
What can I do to get the dropdown to display like image 2 instead of image 3?