CSS Responsive Modal Images

  <html>
<head>
<meta name="viewport" content="width=device-width,
  initial-scale=1.0">
<style>
* {
  margin: 0;
  padding: 0;

  box-sizing: border-box;
}
h1 {
  text-align: center;
  padding:
  20px;
}
.gallery {
  display: flex;
  flex-wrap: wrap;

  justify-content: flex-start;
  padding: 0 15px;
}
.gallery-item {

  position: relative;
  width: calc(25% - 20px);
  height: auto;
  margin:
  10px;
  cursor: pointer;
  transition: transform 0.5s ease;
}

  .gallery-item:hover {
  transform: scale(1.1);
}
/* The Modal
  (background) */
.modal {
  display: none;
  position: fixed;
  z-index:
  1000;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;

  background-color: rgba(0, 0, 0, 0.8);
  align-items: center;

  justify-content: center;
  transition: opacity 0.5s ease;
}
/*
  Modal content (image) */
.modal-content {
  position: relative;
  width:
  90%;
  height: auto;
  max-width: 90%;
  max-height: 90%;
  border-radius:
  5px;
  overflow: hidden;
  animation: zoomIn 0.5s;
}
@keyframes
  zoomIn {
  from {transform: scale(0.6);}
  to {transform: scale(1);}
}

.modal.show {
  display: flex;
  opacity: 1;
}
/* Close button
  */
.close {
  position: absolute;
  top: 10px;
  right: 15px;
  color:
  #ffffff;
  font-size: 35px;
  font-weight: bold;
  cursor: pointer;

  transition: transform 0.3s;
}
/* Caption of modal image */

  .caption {
  position: absolute;
  bottom: 15px;
  width: 100%;

  text-align: center;
  color: #ffffff;
  font-size: 24px;
}
@media
  screen and (max-width: 768px) {
  .gallery-item {
    width: calc(50% - 20px);

  }
}
@media screen and (max-width: 480px) {
  .gallery-item {

  width: calc(100% - 20px);
  }
}
</style>
</head>
<body>

  <h1>Responsive Modal Images</h1>
<div class="gallery">
  <img
  src="img_5terre.jpg" alt="Cinque Terre" class="gallery-item"
  onclick="openModal('modal1', 'Cinque Terre')">

  <img src="img_forest.jpg" alt="Forest" class="gallery-item"
  onclick="openModal('modal2', 'Forest')">
  <img
  src="img_lights.jpg" alt="Northern Lights" class="gallery-item"
  onclick="openModal('modal3', 'Nothern Lights')">

  <img src="img_mountains.jpg" alt="Mountains" class="gallery-item"
  onclick="openModal('modal4', 'Mountains')">
</div>

<div id="modal1" class="modal">
  <span class="close"
  onclick="closeModal('modal1')">&times;</span>
  <img src="img_5terre.jpg"
  alt="Cinque Terre" class="modal-content">
  <div
  class="caption"></div>
</div>
<div id="modal2" class="modal">

  <span class="close" onclick="closeModal('modal2')">&times;</span>
  <img
  src="img_forest.jpg" alt="Forest" class="modal-content">
  <div class="caption"></div>
</div>
<div id="modal3"
  class="modal">
  <span class="close"
  onclick="closeModal('modal3')">&times;</span>
  <img src="img_lights.jpg"
  alt="Northern Lights" class="modal-content">
  <div
  class="caption"></div>
</div>
<div id="modal4" class="modal">

  <span class="close" onclick="closeModal('modal4')">&times;</span>
  <img
  src="img_mountains.jpg" alt="Mountains" class="modal-content">
  <div class="caption"></div>
</div>
<script>
function openModal(modalId, caption) {
  let modal =
  document.getElementById(modalId);
  modal.style.display = "flex";

  modal.classList.add("show");
  let message = modal.querySelector(".caption");

  message.innerText = caption;
}
function closeModal(modalId) {
  let
  modal = document.getElementById(modalId);
  modal.classList.remove("show");

  setTimeout(function () {
    modal.style.display = "none";

  modal.querySelector(".caption").innerText = "";
  }, 300);
}
</script>

  </body>
</html>