CSSとJavaScriptを使用してレスポンシブスライドショーギャラリーを作成するにはどうすればよいですか？

以下は、CSS-

を使用して下部のナビゲーションメニューを作成するためのコードです。

例

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1" />
<style>
* {
   box-sizing: border-box;
}
.Slide {
   display: none;
}
img {
   vertical-align: middle;
   width: 100%;
   height: 400px;
}
.slideContainer {
   max-width: 600px;
   position: relative;
   margin: auto;
}
.prevBtn,
.nextBtn {
   cursor: pointer;
   position: absolute;
   top: 50%;
   width: auto;
   padding: 10px;
   background-color: rgb(255, 255, 75);
   color: rgb(50, 0, 116);
   font-weight: bolder;
   font-size: 18px;
}
.nextBtn {
   right: 0;
}
.Caption {
   color: #fbff09;
   font-weight: bold;
   font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
   font-size: 25px;
   padding: 8px 12px;
   position: absolute;
   bottom: 8px;
   width: 100%;
   text-align: center;
}
.thumbnail:after {
   content: "";
   display: table;
   clear: both;
}
.thumbnail{
   margin-left: 32%;
}
.imageCol {
   float: left;
   width: 16.66%;
}
.thumbImage{
   height: 150px;
   width: 150px;
}
@media only screen and (max-width: 450px) {
   .prevBtn,
   .nextBtn,
   .Caption {
      font-size: 16px;
   }
}
</style>
</head>
<body>
<div class="slideContainer">
<div class="Slide">
<img src="https://images.pexels.com/photos/3540375/pexels-photo-3540375.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=650&w=940" />
<div class="Caption">Photo 1</div>
</div>
<div class="Slide">
<img src="https://images.unsplash.com/photo-1558981001-5864b3250a69?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=750&q=80" />
<div class="Caption">Photo 2</div>
</div>
<div class="Slide">
<img src="https://images.unsplash.com/photo-1584910758141-f7993f9e203d?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=667&q=80" />
<div class="Caption">Photo 3</div>
</div>
<a class="prevBtn"></a>
<a class="nextBtn"></a>
</div>
<br />
<iv class="thumbnail">
<div class="imageCol">
<img class="thumbImage" src="https://images.pexels.com/photos/3540375/pexels-photo-3540375.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=650&w=940" style="width:100%" onclick="setSlide(1)" alt="The Woods">
</div>
<div class="imageCol">
<img class="thumbImage" src="https://images.unsplash.com/photo-1558981001-5864b3250a69?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=750&q=80" style="width:100%" onclick="setSlide(2)" alt="Cinque Terre">
</div>
<div class="imageCol">
<img class="thumbImage" src="https://images.unsplash.com/photo-1584910758141-f7993f9e203d?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=667&q=80" style="width:100%" onclick="setSlide(3)" alt="Mountains and fjords">
</div>
</div>
</div>
<script>
function setSlide(number){
   clearSelected();
   currentSlide(number);
   document.querySelectorAll('.thumbImage')[number-1].style.borderBottom = "6px solid purple";
}
function clearSelected(){
   Array.from(document.querySelectorAll('.thumbImage')).forEach(item=>item.style.borderBottom="");
}
document.querySelector(".prevBtn").addEventListener("click", () => {
   changeSlides(-1);
});
document.querySelector(".nextBtn").addEventListener("click", () => {
   changeSlides(1);
});
var slideIndex = 1;
showSlides(slideIndex);
function changeSlides(n) {
   showSlides((slideIndex += n));
}
function currentSlide(n) {
   showSlides((slideIndex = n));
}
function showSlides(n) {
   var i;
   var slides = document.getElementsByClassName("Slide");
   if (n > slides.length) {
      slideIndex = 1;
   }
   if (n < 1) {
      slideIndex = slides.length;
   }
   Array.from(slides).forEach(item => (item.style.display = "none"));
   slides[slideIndex - 1].style.display = "block";
}
</script>
</body>
</html>