given that this is the a HTML and CSS of my website that is a retail camping company website, what do you recommend I add (I will not be using javascript file)

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="sticky-nav">
            <div class="nav-container">
               <img src="assets/images/logo.svg" alt="Logo" class="logo">

               <h1>Retail Camping Company</h1>
               
               <div class="search-container">
   <form action="/search" method="get">
      <img src="assets/images/search.png" alt="search-icon" class="search-icon">
      <input type="text" name="search" />
      <button type="submit">Search</button>
   </form>
</div>
               <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>
         </div>
      </header>
      <!-- Home Page -->
      <main>
         <section class="slideshow-section">
            <!-- Insert slide show here -->
            <div class="slideshow-container">
               <div class="mySlides fade">
                  <img src="https://via.placeholder.com/600x400" alt="Tents" style="width:100%">
               </div>
               <div class="mySlides fade">
                  <img src="https://via.placeholder.com/600x400" alt="Cookers" style="width:100%">
               </div>
               <div class="mySlides fade">
                  <img src="https://via.placeholder.com/600x400" alt="Camping Gear" style="width:100%">
               </div>
                          <a class="prev" onclick="plusSlides(-1)">❮</a>
           <a class="next" onclick="plusSlides(1)">❯</a>
        </div>
        <div style="text-align:center">
           <span class="dot" onclick="currentSlide(1)"></span>
           <span class="dot" onclick="currentSlide(2)"></span>
           <span class="dot" onclick="currentSlide(3)"></span>
        </div>
     </section>
     <section class="about-section">
        <p>Welcome to Retail Camping Company, your one-stop-shop for all your camping equipment needs. Discover our premium offers on tents, cookers, camping gear, and furniture.</p>
     </section>
     <section class="featured-section">
        <h2>Featured Products</h2>
        <div class="featured-container">
           <div class="featured-product">
              <img src="https://via.placeholder.com/150x150" alt="Featured Product">
              <h3>Product Name</h3>
              <p>Short product description.</p>
           </div>
           <div class="featured-product">
              <img src="https://via.placeholder.com/150x150" alt="Featured Product">
              <h3>Product Name</h3>
              <p>Short product description.</p>
           </div>
           <div class="featured-product">
              <img src="https://via.placeholder.com/150x150" alt="Featured Product">
              <h3>Product Name</h3>
              <p>Short product description.</p>
           </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>

<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>




      </main>
      <footer>
  <div class="footer-container">

         <div class="footer-item">
            <p>Subscribe To Our Newsletter:</p>
               <form action="subscribe.php" method="post">
                  <input type="email" name="email" placeholder="Enter your email" required>
                  <button type="submit">Subscribe</button>
               </form>
            </div>
    <div class="footer-item address-container">

      <p>        Get In Contact:</p>
      <p>Email: info@retailcampingcompany.com</p>
      <p>Phone: +35699382994</p>
      <p>Triq Malta,<br>Sliema 12345</p>
      
    </div>
<div class="footer-item google-maps-container">
   <p>Where To Find Us:</p>
  <iframe src="https://www.google.com/maps/embed?pb=!1m14!1m8!1m3!1d12928.30174160605!2d14.5091557!3d35.8961681!3m2!1i1024!2i768!4f13.1!3m3!1m2!1s0x130e452d3081f035%3A0x61f492f43cae68e4!2sCity%20Gate!5e0!3m2!1sen!2smt!4v1682559564194!5m2!1sen!2smt" width="650" height="200" style="border:0;" allowfullscreen="" loading="lazy" referrerpolicy="no-referrer-when-downgrade"></iframe>
   </div>
 
      <div class="footer-item social-links-container">
      <p>Follow Us On:</p>
      <ul class="social-links">
        <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>
      </div>
      

  </div>
</footer>
      <script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
      <script src="script.js"></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;
}

.sticky-nav {
  position: -webkit-sticky;
  position: sticky;
  top: 0;
  z-index: 1000;
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
}
.search-container {
   display: inline-block;
   position: relative;
}

.search-container input[type="text"] {
padding: 0.8rem;
border: none;
border-bottom: 1.5px solid #32612D;
outline: none;
color: #32612D;
font-size: 1rem;
background-color: transparent;
margin-right: 30rem;
margin-bottom: 12px;
width: 65%;
}

.search-container input[type="text"]::placeholder {
color: #32612D;
opacity: 0.5;
}
.search-icon {
  margin-right: 0.8rem;
  width: 24px;
  height: auto;
  vertical-align: middle;
  position: absolute;
  top: 50%;
  margin-top: -16px; 
  
}


.search-container input[type="text"]:focus {
border-color: #ADC3AB;
}

.search-container button[type="submit"] {
display: none;
}
.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;
  position: relative;
  transition: color 0.3s ease;
}

@media screen and (max-width: 768px) {
  .nav-container {
    flex-direction: column;
  }
  h1 {
    margin-bottom: 1rem;
  }
}
nav ul li a {
  text-decoration: none;
  color: #32612D;
  position: relative;
  transition: color 0.3s ease;
}


nav ul li a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background-color: #000;
  transform: scaleX(0);
  transition: transform 0.3s;
}
nav ul li a:hover {
  color: #000000;
}
nav ul li a:hover::after {
  transform: scaleX(1);
}

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

.mySlides {
display: none;
}

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

/* Slideshow navigation */
.prev, .next {
  cursor: pointer;
  position: absolute;
  top: 50%;
  width: auto;
  margin-top: -22px;
  padding: 16px;
  color: #32612D;
  font-weight: bold;
  font-size: 18px;
  transition: 0.6s ease;
  border-radius: 0 3px 3px 0;
  user-select: none;
}

.next {
  right: 0;
  border-radius: 3px 0 0 3px;
}

.prev:hover, .next:hover {
  background-color: rgba(255,255,255,0.8);
}

.dot {
  cursor: pointer;
  height: 15px;
  width: 15px;
  margin: 0 2px;
  background-color: #bbb;
  border-radius: 50%;
  display: inline-block;
  transition: background-color 0.6s ease;
}

.dot:hover {
  background-color: #717171;
}

.fade {
  -webkit-animation-name: fade;
  -webkit-animation-duration: 1.5s;
  animation-name: fade;
  animation-duration: 1.5s;
}

@-webkit-keyframes fade {
  from {opacity: .4}
  to {opacity: 1}
}

@keyframes fade {
  from {opacity: .4}
  to {opacity: 1}
}

.about-section {
  
  padding: 1rem;
  text-align: center;
  margin: 1rem 0;
}

.featured-section {
  
  padding: 1rem;
  text-align: center;
  margin: 1rem 0;
}

.featured-section h2 {
  font-size: 1.5rem;
  margin-bottom: 1rem;
}

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

.featured-product {
  width: 150px;
  padding: 1rem;
  background-color: #ADC3AB;
  border-radius: 5px;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
  transition: all 0.3s ease;
  margin: 0.5rem;
}

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

.featured-product img {
  width: 100%;
  height: auto;
  margin-bottom: 1rem;
  border-radius: 5px;
}

.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);
}
.modalBtn{
  background-color: #ADC3AB;
   color: #32612D;
   padding: 0.5rem;
   border: none;
   border-radius: 5px;
   cursor: pointer;
}

.buts {

text-align: center;

}
.footer-item.address-container p {
  margin: 0; 
  text-align: left;
}
.footer-item p {
  
  text-align: center;
}
.add{
text-align: center;
}

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

footer {
  background: #32612D;
  padding: 1rem;
  text-align: center;
  margin-top: auto;
}


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

.footer-item {
  margin: 1rem 2rem;
}

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;
}
}

.footer-item iframe {
  width: 100%;
  height: 200px;
}

.footer-item form {
   display: inline-flex;
   align-items: center;
}
.footer-item input[type="email"] {
   padding: 0.5rem;
   border: none;
   border-radius: 5px;
   margin-right: 0.5rem;
}
.footer-item button {
   background-color: #ADC3AB;
   color: #32612D;
   padding: 0.5rem;
   border: none;
   border-radius: 5px;
   cursor: pointer;
}
.footer-item button:hover {
   background-color: #32612D;
   color: #fff;
}
.social-links-container {
  order: 2;
}


.address-container {
  order: 1;

}

.google-maps-container {
  order: 0;
}