given that this is my css and html, add a small hover animation that quickly draws a line under what is being hovered over in the navigation bard:

HTML:
<!DOCTYPE html>
<html lang=:"en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=Cabin:wght@400;700&display=swap">
<link rel="stylesheet" href="style/style.css" />
<title>Camping Equipment - Retail Camping Company</title>
</head>
<body>
<header>
<div class="nav-container">
<img src="C:/Users/Kaddra52/Desktop/DDW/assets/images/logo.svg" alt="Logo" class="logo">
<h1>Retail Camping Company</h1>
<nav>
<ul>
<li><a href="index.html">Home</a></li>
            <li><a href="camping-equipment.html">Camping Equipment</a></li>
            <li><a href="furniture.html">Furniture</a></li>
            <li><a href="reviews.html">Reviews</a></li>
            <li><a href="basket.html">Basket</a></li>
            <li><a href="offers-and-packages.html">Offers and Packages</a></li>
</ul>
</nav>
</div>
</header>
   <!-- Home Page -->
   <main>
      <section>
         <!-- Insert slide show here -->
         <div class="slideshow-container">
            <div class="mySlides">
               <img src="https://via.placeholder.com/600x400" alt="Tents" style="width:100%">
            </div>
            <div class="mySlides">
               <img src="https://via.placeholder.com/600x400" alt="Cookers" style="width:100%">
            </div>
            <div class="mySlides">
               <img src="https://via.placeholder.com/600x400" alt="Camping Gear" style="width:100%">
            </div>
         </div>
      </section>
      <section>
         <!-- Display special offers and relevant images -->
         <div class="special-offers-container">
            <div class="special-offer">
               <img src="https://via.placeholder.com/200x200" alt="Tent Offer">
               <p>20% off premium tents!</p>
            </div>
            <div class="special-offer">
               <img src="https://via.placeholder.com/200x200" alt="Cooker Offer">
               <p>Buy a cooker, get a free utensil set!</p>
            </div>
            <div class="special-offer">
               <img src="https://via.placeholder.com/200x200" alt="Furniture Offer">
               <p>Save on camping furniture bundles!</p>
            </div>
         </div>
      </section>
      <section class="buts">
         <!-- Modal pop-up window content here -->
         <button id="modalBtn">Special Offer!</button>
         <div id="modal" class="modal">
            <div class="modal-content">
               <span class="close">×</span>
               <p>Sign up now and receive 10% off your first purchase!</p>
            </div>
         </div>
      </section>
   </main>
   <footer>
      <p>Follow us on social media:</p>
      <ul>
         <li><a href="https://www.facebook.com">Facebook</a></li>
         <li><a href="https://www.instagram.com">Instagram</a></li>
         <li><a href="https://www.twitter.com">Twitter</a></li>
      </ul>
   </footer>
   <script>
      // Get modal element
      var modal = document.getElementById('modal');
      // Get open model button
      var modalBtn = document.getElementById('modalBtn');
      // Get close button
      var closeBtn = document.getElementsByClassName('close')[0];
         // Listen for open click
         modalBtn.addEventListener('click', openModal);
         // Listen for close click
         closeBtn.addEventListener('click', closeModal);
         // Listen for outside click
         window.addEventListener('click', outsideClick);
         
         // Function to open modal
         function openModal() {
         modal.style.display = 'block';
         }
         
         // Function to close modal
         function closeModal() {
         modal.style.display = 'none';
         }
         
         // Function to close modal if outside click
         function outsideClick(e) {
         if (e.target == modal) {
         modal.style.display = 'none';
         }
         }
      </script>
   </body>
</html>
CSS:
html, body, h1, h2, h3, h4, p, a, ul, li, div, main, header, section, footer, img {
  margin: 0;
  padding: 0;
  border: 0;
  font-size: 100%;
  font-family: inherit;
  vertical-align: baseline;
  box-sizing: border-box;
}

body {
  font-family: 'Cabin', sans-serif;
  line-height: 1.5;
  color: #333;
  width: 100%;
  margin: 0;
  padding: 0;
  min-height: 100vh;
  flex-direction: column;
  display: flex;
  background-image: url("../assets/images/cover.jpg");
  background-size: cover;
}
header {
  background: #00000000;
  padding: 0.5rem 2rem;
  text-align: center;
  color: #32612D;
  font-size: 1.2rem;
}
main{
  flex-grow: 1;
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
}

.logo {
  width: 50px;
  height: auto;
  margin-right: 1rem;
}

h1 {
  flex-grow: 1;
  text-align: left;
}

nav ul {
  display: inline;
  list-style: none;
}

nav ul li {
  display: inline;
  margin-left: 1rem;
}

nav ul li a {
  text-decoration: none;
  color: #32612D;
}

nav ul li a:hover {
  color: #000000;
}

@media screen and (max-width: 768px) {
  .nav-container {
    flex-direction: column;
  }
  h1 {
    margin-bottom: 1rem;
  }
}

.slideshow-container {
width: 100%;
position: relative;
margin: 1rem 0;
}

.mySlides {
display: none;
}

.mySlides img {
width: 100%;
height: auto;
}

.special-offers-container {
display: flex;
justify-content: space-around;
align-items: center;
flex-wrap: wrap;
margin: 1rem 0;
}

.special-offer {
width: 200px;
padding: 1rem;
text-align: center;
margin: 1rem;
background-color: #ADC3AB;
border-radius: 5px;
box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
transition: all 0.3s ease;
}

.special-offer:hover {
box-shadow: 0 8px 16px rgba(0, 0, 0, 0.2);
transform: translateY(-5px);
}

.special-offer img {
width: 100%;
height: auto;
margin-bottom: 0.5rem;
border-radius: 5px;
}

.modal {
display: none;
position: fixed;
left: 0;
top: 0;
width: 100%;
height: 100%;
background-color: rgba(0, 0, 0, 0.5);
z-index: 1;
overflow: auto;
align-items: center;
}

.modal-content {
background-color: #fefefe;
padding: 2rem;
margin: 10% auto;
width: 30%;
min-width: 300px;
max-width: 80%;
text-align: center;
border-radius: 5px;
box-shadow: 0 1px 8px rgba(0, 0, 0, 0.1);
}
.buts{

text-align: center;
}

.close {
display: block;
text-align: right;
font-size: 2rem;
color: #333;
cursor: pointer;
}

footer {
  position: relative;
  bottom: 0px;
  background: #32612D;
  padding: 1rem;
  text-align: center;
  margin-top: auto;
}

footer p {
color: #fff;
margin-bottom: 1rem;
}

footer ul {
list-style: none;
}

footer ul li {
display: inline;
margin: 0.5rem;
}

footer ul li a {
text-decoration: none;
color: #fff;
}

@media screen and (max-width: 768px) {
.special-offers-container {
flex-direction: column;
}
}

@media screen and (max-width: 480px) {


h1 {
display: block;
margin-bottom: 1rem;
}
}

.catalog {
display: flex;
flex-wrap: wrap;
justify-content: center;
margin: 2rem 0;
}

.catalog-item {
width: 200px;
padding: 1rem;
margin: 1rem;
background-color: #ADC3AB;
border-radius: 5px;
box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
text-align: center;
}

.catalog-item:hover {
box-shadow: 0 8px 16px rgba(0, 0, 0, 0.2);
}

.catalog-item img {
width: 100%;
height: auto;
margin-bottom: 0.5rem;
border-radius: 5px;
}

.catalog-item h3 {
margin-bottom: 0.5rem;
}

.catalog-item p {
margin-bottom: 0.5rem;
}

.catalog-item button {
background-color: #32612D;
color: #fff;
padding: 0.5rem;
border: none;
border-radius: 5px;
cursor: pointer;
}

.catalog-item button:hover {
background-color: #ADC3AB;
}