How to fix the navbar hover issue CSS - css

Question

I am working on navbar in bootstrap 4. I am experiencing issue when i hover on the nav links. I have added border bottom on hover for navlinks. But when the hover is made the entire navbar moves. I have pasted what i have done so far.
<nav class="navbar navbar-expand-lg navbar-dark bg-dark">
<a class="navbar-brand" href="#">
<img src="#" />
</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarSupportedContent">
<ul class="navbar-nav mr-auto">
<li class="nav-item active">
<a class="nav-link" href="#">First item</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Second Item</a>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Dropdown
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown">
<a class="dropdown-item" href="#">Action</a>
<a class="dropdown-item" href="#">Another action</a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="#">Something else here</a>
</div>
</li>
</ul>
<div class="my-2 my-lg-0">
</div>
</div>
</nav>
<style>
.navbar-dark .navbar-nav .nav-link:hover,
.navbar-dark .navbar-nav .nav-link:focus {
color: rgba(255, 255, 255, 0.75);
border-bottom: 2px solid #fff;
}
</style>

Answer 1

The reason it is shifting is because you have no border, and then all of a sudden a 2px border is added on hover. The way to fix this is by adding a 2px transparent border to the regular/unhovered state.
.navbar-dark .navbar-nav .nav-link {
border-bottom: 2px solid transparent;
}