CSSとJavaScriptを使用して見積もりのスライドショーを作成するにはどうすればよいですか？

CSSとJavaScriptを使用して見積もりスライドショーを作成するには、コードは次のとおりです-

例

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1" />
<style>
   body {
      font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
   }
   h1 {
      text-align: center;
   }
   * {
      box-sizing: border-box;
   }
   .Slide {
      display: none;
   }
   img {
      vertical-align: middle;
      width: 100%;
      height: 400px;
   }
   .slideContainer {
      max-width: 600px;
      margin: 10px;
      position: relative;
      margin: auto;
   }
   .prevBtn, .nextBtn {
      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: -40px;
   }
   .prevBtn {
      left: -40px;
   }
   .Caption {
      color: #500070;
      font-weight: bold;
      font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
      font-size: 25px;
      padding: 8px 12px;
      position: absolute;
      width: 100%;
      text-align: center;
   }
   .Navdot {
      cursor: pointer;
      height: 15px;
      width: 15px;
      margin: 0 2px;
      background-color: rgb(54, 5, 117);
      border-radius: 50%;
      display: inline-block;
      transition: background-color 0.6s ease;
      display: inline-block;
      margin-top: 30px;
   }
   .selected, .Navdot:hover {
      background-color: #d9ff00;
   }
   @media only screen and (max-width: 450px) {
      .prevBtn, .nextBtn, .Caption {
         font-size: 16px;
      }
   }
</style>
</head>
<body>
<h1>Quote slideShow</h1>
<hr />
<div class="slideContainer">
<div class="Slide">
<h1>"The way to get started is to quit talking and begin doing."</h1>
<div class="Caption">- Walt Disney</div>
</div>
<div class="Slide">
<h1>
"If life were predictable it would cease to be life, and be without flavor."
</h1>
<div class="Caption">-Eleanor Roosevelt</div>
</div>
<div class="Slide">
<h1>"Life is what happens when you're busy making other plans."</h1>
<div class="Caption">-John Lennon</div>
</div>
<a class="prevBtn">❮</a>
<a class="nextBtn">❯</a>
</div>
<br />
<div style="text-align:center">
<span class="Navdot" onclick="currentSlide(1)"></span>
<span class="Navdot" onclick="currentSlide(2)"></span>
<span class="Navdot" onclick="currentSlide(3)"></span>
</div>
<script>
   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");
      var dots = document.getElementsByClassName("Navdot");
      if (n > slides.length) {
         slideIndex = 1;
      }
      if (n < 1) {
         slideIndex = slides.length;
      }
      Array.from(slides).forEach(item => (item.style.display = "none"));
      Array.from(dots).forEach(
         item => (item.className = item.className.replace(" selected", ""))
      );
      slides[slideIndex - 1].style.display = "block";
      dots[slideIndex - 1].className += " selected";
   }
</script>
</body>
</html>