.gallery {
  display: flex;
  flex-wrap: wrap;
}

.gallery-item {
  flex: 0 0 33.33%;
  padding: 10px;
  box-sizing: border-box;
  cursor: pointer;
}

.gallery-item img {
  width: 100%;
  height: auto;
}

.lightbox {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.9);
  overflow: auto;
}

.lightbox-content {
  position: relative;
  margin: auto;
  width: 80%;
  max-width: 800px;
  text-align: center;
  color: #fff;
}

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

.close-btn {
  position: absolute;
  top: 15px;
  right: 15px;
  font-size: 30px;
  color: #fff;
  cursor: pointer;
}

.prev,
.next {
  position: absolute;
  top: 50%;
  font-size: 30px;
  color: #fff;
  cursor: pointer;
}

.prev {
  left: 15px;
}

.next {
  right: 15px;
}

@media only screen and (max-width: 600px) {
  .gallery-item {
    flex: 0 0 100%;
  }
}