How to create a responsive slideshow with CSS and JavaScript

<!-- Slideshow container -->
<div class="slideshow-container">
  <!-- Full-width images with number and caption text -->
  <div class="cssSlides fade">
    <div class="number">1 / 4</div>
    <img src="picture-1.jpg" style="width:100%">
    <div class="text">Caption Text</div>
  </div>
  <div class="cssSlides fade">
    <div class="number">2 / 4</div>
    <img src="picture-2.jpg" style="width:100%">
    <div class="text">Caption Two</div>
  </div>


  <div class="cssSlides fade">
    <div class="number">3 / 4</div>
    <img src="picture-3.jpg" style="width:100%">
    <div class="text">Caption Three</div>
  </div>


  <div class="cssSlides fade">
    <div class="number">4 / 4</div>
    <img src="picture-4.jpg" style="width:100%">
    <div class="text">Caption Three</div>
  </div>


  <!-- Next and previous buttons -->
  <a class="prev" onclick="Slides(-1)">❮</a>
  <a class="next" onclick="Slides(1)">❯</a>
</div>
<br>


<!-- The dots -->
<div style="text-align:center">
  <span class="dot" onclick="Slide(1)"></span>
  <span class="dot" onclick="Slide(2)"></span>
  <span class="dot" onclick="Slide(3)"></span>
</div>
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Step 2

 {box-sizing:border-box}


/* Slideshow container */
.slideshow-container {
  max-width: 1000px;
  position: relative;
  margin: auto;
}


/* Hide the images by default */
.cssSlides {
  display: none;
}


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


/* Position the "next button" to the right */
.next {
  right: 0;
  border-radius: 3px 0 0 3px;
}


/* On hover, add a black background color with a little bit see-through */
.prev:hover, .next:hover {
  background-color: rgba(0,0,0,0.8);
}


/* Caption text */
.text {
  color: #f2f2f2;
  font-size: 15px;
  padding: 8px 12px;
  position: absolute;
  bottom: 8px;
  width: 100%;
  text-align: center;
}


/* Number text (1/4 etc) */
.number {
  color: #f2f2f2;
  font-size: 12px;
  padding: 8px 12px;
  position: absolute;
  top: 0;
}


/* The dots */
.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;
}


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


/* Fading animation */
.fade {
  animation-name: fade;
  animation-duration: 1.5s;
}


@keyframes fade {
  from {opacity: .4}
  to {opacity: 1}
}
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Step 3

let slideIndex = 1;
showSlides(slideIndex);


// Next/previous controls
function Slides(n) {
  showSlides(slideIndex += n);
}


// Thumbnail image controls
function Slide(n) {
  showSlides(slideIndex = n);
}


function showSlides(n) {
  let i;
  let slides = document.getElementsByClassName("cssSlides");
  let dots = document.getElementsByClassName("dot");
  if (n > slides.length) {slideIndex = 1}
  if (n < 1) {slideIndex = slides.length}
  for (i = 0; i < slides.length; i++) {
    slides[i].style.display = "none";
  }
  for (i = 0; i < dots.length; i++) {
    dots[i].className = dots[i].className.replace(" active", "");
  }
  slides[slideIndex-1].style.display = "block";
  dots[slideIndex-1].className += " active";
}
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Automatic Slideshow

let slideIndex = 0;
showSlides();


function showSlides() {
  let i;
  let slides = document.getElementsByClassName("cssSlides");
  for (i = 0; i < slides.length; i++) {
    slides[i].style.display = "none";
  }
  slideIndex++;
  if (slideIndex > slides.length) {slideIndex = 1}
  slides[slideIndex-1].style.display = "block";
  setTimeout(showSlides, 2000); // Change image every 2 seconds
}
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