gallery.css

.gallery {
  display: flex;
  flex-flow: row nowrap;
  width: 100%;
}

.thumbnails-wrapper {
  max-width: calc(100% / 6);
  flex-basis: calc(100% / 6);
  padding: 0.5rem;
}

.thumbnails-overflow-container {
  position: relative;
  height: 100%;
}

.thumbnails-overflow {
  position: absolute;
  width: 100%;
  height: 100%;
  overflow: hidden;
}

.image-display-wrapper {
  max-width: calc(5 * 100% / 6);
  flex-basis: calc(5 * 100% / 6);
}

.thumbnails-list-container {
  height: 100%;
}

.thumbnails-list {
  display: flex;
  flex-direction: column;
  list-style: none;
  overflow-y: scroll;
  scrollbar-width: none;
  scroll-padding-top: 0px;
  scroll-behavior: smooth;
  scroll-snap-type: y;
  margin: 0;
  padding: 0;
  height: 100%;
}

.thumbnail-button {
  appearance: none;
  border: 2px solid transparent;
  width: 100%;
  background: transparent;
  padding: 0;
}

.thumbnail-button:focus {
  outline: none;
  border: 2px solid black;
}

.images-display-container {
  padding: 0 0.5rem;
}

.images-list {
  display: flex;
  flex-flow: row nowrap;
  list-style: none;
  overflow-x: scroll;
  scroll-padding-left: 0px;
  scroll-snap-type: x mandatory;
  margin: 0;
  padding: 0;
  scrollbar-width: none;
}

.images-list:focus-visible {
  outline: 2px solid black;
}

.image-item {
  flex: 0 0 100%;
  scroll-snap-align: start;
}

.aspect-ratio-4-3-wrapper {
  position: relative;
  overflow: hidden;
  height: 0;
  padding-top: calc(400% / 3);
}

.aspect-ratio-child {
  position: absolute;
  width: 100%;
  height: 100%;
  top: 0;
  left: 0;
  display: flex;
  align-items: center;
}

img {
  width: 100%;
  display: block;
}

@media screen and (max-width: 40rem) {
  .thumbnails-wrapper {
    display: none;
  }

  .image-display-wrapper {
    max-width: 100%;
    flex-basis: 100%;
  }
}