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CSS

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HTML 

              
                <div id="root"></div>
!

CSS 

              
                #root {
  padding: 20px;
}

.vertical-gallery {
  &.gallery-container {
    display: flex;
    position: relative;
    justify-content: center;
    margin: 0 60px 0 80px;
    width: 100%;
    max-width: calc((100vh - 230px) * 0.75);
    height: fit-content;

    .thumbnails {
      display: flex;
      position: absolute;
      top: 0;
      left: -80px;
      flex-direction: column;
      transform: none;
      gap: 4px;
    }
  }

  &.single-image {
    .thumbnails,
    .scrollbar {
      display: none;
    }

    .slides {
      overflow-y: hidden;
    }
  }

  .thumbnails div {
    position: relative;
    width: 48px;
    height: 64px;
    border-radius: 2px;
    cursor: pointer;

    img {
      width: 100%;
      height: auto;
      border-radius: 2px;
      filter: brightness(0.97);
    }

    &.selected {
      opacity: 0.5;
    }

    &.more-images {
      height: auto;
      cursor: pointer;
      padding: 10px 0;
      text-align: center;
      color: #363636;
    }
  }

  .scrollbar {
    display: block;
    position: absolute;
    top: 0;
    left: -16px;
    width: 1px;
    height: 100%;
    background: #ccc;
  }

  .thumb {
    position: absolute;
    transition: 0.3s height ease-in-out;
    width: 1px;
    height: 0;
    background: #000;
  }

  .slide-container {
    width: 100%;
    height: 0;
    padding-top: 133.333%;
  }

  .slides {
    scrollbar-width: none;

    &::-webkit-scrollbar {
      display: none;
    }

    display: grid;
    position: absolute;
    top: 0;
    left: 0;
    grid-auto-flow: row;
    height: 100%;
    overflow-y: hidden;
    gap: 0;
    scroll-snap-type: y mandatory;
    scroll-behavior: smooth;

    // Clever hack to avoid MacOS inertia breaking the scroll
    &:hover {
      overflow-y: auto;
    }

    &:not(:hover) {
      animation: 0.3s delay-overflow cubic-bezier(0.35, -0.7, 1, 1);
    }

    > div {
      display: flex;
      position: relative;
      scroll-snap-align: start;

      &::after {
        content: "";
        position: absolute;
        top: 0;
        left: 0;
        opacity: 0.03;
        width: 100%;
        height: 100%;
        background-color: #000;
        pointer-events: none;
      }
    }

    img {
      width: 100%;
      cursor: pointer;
      object-fit: contain;

      &:first-of-type {
        min-height: 100%;
      }
    }
  }
}

@keyframes delay-overflow {
  from {
    overflow: auto;
  }
}
!

JS 

              
                class VerticalGallery extends React.PureComponent {
  state = {
    selectedIndex: 0,
    galleryHeight: 120,
    isScrolling: false
  };

  galleryRef = React.createRef();

  thumbnailsRef = React.createRef();

  intervalRef = null;

  componentDidMount() {
    this.updateGalleryHeight();
    this.intervalRef = setInterval(() => this.snapGallery(), 300);
  }

  componentDidUpdate() {
    this.updateGalleryHeight();
  }

  componentWillUnmount() {
    clearInterval(this.intervalRef);
  }

  updateGalleryHeight() {
    const gallery = this.galleryRef.current;
    if (gallery) {
      this.setState({ galleryHeight: gallery.offsetHeight });
    }
  }

  snapGallery() {
    const gallery = this.galleryRef.current;
    const thumbnails = this.thumbnailsRef.current;
    const { selectedIndex, galleryHeight, isScrolling } = this.state;
    if (
      !gallery.matches(":hover") &&
      !thumbnails.matches(":hover") &&
      !isScrolling
    ) {
      this.setState({ isScrolling: true }, () => {
        setTimeout(() => this.setState({ isScrolling: false }), 300);
      });
      gallery.scrollTop = galleryHeight * selectedIndex;
    }
  }

  render() {
    const { images, displayTitle } = this.props;
    const { selectedIndex, galleryHeight, isScrolling } = this.state;
    if (!images) return null;
    const imageCount = images.length;
    const imageScrollHeight = galleryHeight / imageCount;
    const maxThumbnails = Math.floor(galleryHeight / 68);
    let visibleThumbnails = maxThumbnails;
    if (maxThumbnails < imageCount) {
      if (galleryHeight - 40 < maxThumbnails * 68) visibleThumbnails -= 1;
    }
    const isFirstRender = !this.galleryRef.current;

    return (
      <div className="vertical-gallery gallery-container">
        <div className="thumbnails" ref={this.thumbnailsRef}>
          {images.slice(0, visibleThumbnails).map((image, index) => {
            const selected = index === selectedIndex;
            return (
              <div
                key={`thumbnail_${image.imageUrl}`}
                className={selected ? "selected" : undefined}
                onClick={() => {
                  this.setState(
                    { selectedIndex: index, isScrolling: true },
                    () => {
                      setTimeout(
                        () => this.setState({ isScrolling: false }),
                        Math.abs(selectedIndex - index) * 150 + 300
                      );
                    }
                  );
                  this.galleryRef.current.scrollTop = galleryHeight * index;
                }}
              >
                <img alt="" src={image.imageUrl} />
              </div>
            );
          })}
          {!isFirstRender && imageCount > visibleThumbnails && (
            <div
              className="more-images"
              onClick={() => {
                this.openModal(0);
              }}
            >
              <span>+{imageCount - visibleThumbnails}</span>
            </div>
          )}
        </div>
        <div className="scrollbar">
          <div
            className="thumb"
            style={{ height: `${(selectedIndex + 1) * imageScrollHeight}px` }}
          />
        </div>
        <div className="slide-container">
          <div
            className="slides"
            ref={this.galleryRef}
            onScroll={() => {
              if (!isScrolling) {
                const { scrollTop } = this.galleryRef.current;
                const index = Math.round(scrollTop / galleryHeight);
                this.setState({ selectedIndex: index });
              }
            }}
          >
            {images
              .slice(0, isFirstRender ? 1 : undefined)
              .map((image, index) => (
                <div
                  key={image.imageUrl}
                  className="slide"
                  onClick={() => {
                    this.openModal(index);
                  }}
                >
                  <img src={image.imageUrl} alt={displayTitle} />
                </div>
              ))}
          </div>
        </div>
      </div>
    );
  }
}

const props = {
  images: [
    { imageUrl: "https://picsum.photos/id/1067/540/720" },
    { imageUrl: "https://picsum.photos/id/122/540/720" },
    { imageUrl: "https://picsum.photos/id/188/540/720" },
    { imageUrl: "https://picsum.photos/id/249/540/720" },
    { imageUrl: "https://picsum.photos/id/257/540/720" },
    { imageUrl: "https://picsum.photos/id/259/540/720" },
    { imageUrl: "https://picsum.photos/id/283/540/720" },
    { imageUrl: "https://picsum.photos/id/288/540/720" },
    { imageUrl: "https://picsum.photos/id/299/540/720" }
  ],
  displayTitle: "Lorem ipsum"
};

ReactDOM.render(
  <VerticalGallery {...props} />,
  document.getElementById("root")
);
!
999px

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