index.css

.carousel {
    /* for absolute position of next/previous button */
    position: relative;
    /* animate the background-color when entering fullscreen */
    transition: background-color 0.3s ease-out;
}

.carousel.is-fullscreen {
    /* stretch to 100% browser width/height */
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    background-color: black; /* fallback */
    background-color: rgba(0, 0, 0, 0.9); /* backdrop color */
}

.carousel-list {
    list-style: none;
    /* clear whitespace around .carousel-item */
    font-size: 0;
    /* center align thumbnails when not enhanced with JavaScript */
    text-align: center;
}

.carousel.is-enhanced .carousel-list {
    list-style: none;
    /* show a tiny bit of the image positioned outside the viewport */
    padding-left: 3%;
    /* place items on 1 line */
    white-space: nowrap;
    /* hide images positioned outside .carousel-list */
    overflow-x: hidden;
    /* clear whitespace around .carousel-item */
    font-size: 0;
}

.carousel.is-fullscreen .carousel-list {
    /* in fullscreen, don't show a bit of the previous image */
    padding-left: 0;
    /* vertically center */
    position: absolute;
    top: 50%;
    -webkit-transform: translateY(-50%); /* Ch <36, Saf 5.1+, iOS < 9.2, An =<4.4.4 */
    -ms-transform: translateY(-50%); /* IE 9 */
    transform: translateY(-50%); /* IE 10, Fx 16+, Op 12.1+ */
}

.carousel-item {
    display: inline-block;
    /* add some spacing between items */
    margin-right: 2%;
}

.carousel.is-enhanced .carousel-item {
    /*
     * Initially, position each item 200% of it's own width to the left,
     * so that they can animate back into the viewport again
     */
    -webkit-transform: translateX(-200%); /* Ch <36, Saf 5.1+, iOS < 9.2, An =<4.4.4 */
    -ms-transform: translateX(-200%); /* IE 9 */
    transform: translateX(-200%); /* IE 10, Fx 16+, Op 12.1+ */
}

.carousel.is-enhanced .carousel-item.is-animating-left {
    transition: transform 0.2s ease-out;
    /* triggered 'next': animate to default - 100% */
    -webkit-transform: translateX(-300%); /* Ch <36, Saf 5.1+, iOS < 9.2, An =<4.4.4 */
    -ms-transform: translateX(-300%); /* IE 9 */
    transform: translateX(-300%); /* IE 10, Fx 16+, Op 12.1+ */
}

.carousel.is-enhanced .carousel-item.is-animating-right {
    transition: transform 0.2s ease-out;
    /* triggered 'previous': animate to default + 100% */
    -webkit-transform: translateX(-100%); /* Ch <36, Saf 5.1+, iOS < 9.2, An =<4.4.4 */
    -ms-transform: translateX(-100%); /* IE 9 */
    transform: translateX(-100%); /* IE 10, Fx 16+, Op 12.1+ */
}

.carousel.is-enhanced .carousel-item.is-animating-initial {
    /* animate back to initial state */
    transition: transform 0.2s ease-out;
}

.carousel.is-fullscreen .carousel-item {
    /*
     * Show item on 100% screen width. Once the nested fullscreen
     * <img> has been loaded, it is stretched to this container.
     */
    width: 100%;
    /* in fullscreen, remove the spacing between items */
    margin-right: 0;
}

.carousel-img {
    /* limit thumbnail width when not enhanced with JavaScript */
    max-width: 300px;
    /* remove the border on images inside links in IE 10- */
    border-style: none;
}

.carousel.is-enhanced .carousel-img {
    /* restore max-width; use value from `sizes` attribute instead */
    max-width: none;
    /* enable single-finger horizontal panning gestures */
    touch-action: pan-x;
    /* prevent accidentally selecting an image while dragging */
    -webkit-user-select: none; /* Chrome / Safari */
    -moz-user-select: none; /* Firefox  */
    -ms-user-select: none; /* IE 10+ */
    user-select: none;
}

.carousel.is-fullscreen .carousel-img {
    /* show image on full width of the browser */
    width: 100%;
}

.carousel-previous,
.carousel-next,
.carousel-close {
    display: none; /* hide when not enhanced with JS */
    position: absolute;
    color: white;
    background-color: black; /* fallback */
    background-color: rgba(0, 0, 0, 0.75);
    cursor: pointer;
    z-index: 1;
}

.carousel.is-enhanced .carousel-previous,
.carousel.is-enhanced .carousel-next {
    display: block; /* show next/previous when enhanced with JS */
}

.carousel-previous,
.carousel-next {
    width: 48px;
    height: 48px;
    padding: 0;
    /* vertically center */
    top: 0;
    bottom: 0;
    margin: auto;
    /* end vertically center */
    border: 0;
}

.carousel-next {
    right: 0;
}

/* triangle left/right */
.carousel-previous:before,
.carousel-next:before {
    content: '';
    display: inline-block;
    width: 0;
    height: 0;
    border-style: solid;
    border-color: transparent ;
}

/* triangle left */
.carousel-previous:before {
    border-width: 8px 14px 8px 0;
    border-right-color: white;
}

/* triangle right */
.carousel-next:before {
    border-width: 8px 0 8px 14px;
    border-left-color: white;
}

.carousel-close {
    top: -2px;
    /* horizontally center */
    left: 50%;
    -webkit-transform: translateX(-50%); /* Ch <36, Saf 5.1+, iOS < 9.2, An =<4.4.4 */
    -ms-transform: translateX(-50%); /* IE 9 */
    transform: translateX(-50%); /* IE 10, Fx 16+, Op 12.1+ */
    /* end horizontally center */
    padding: 16px;
    font-size: 1rem;
    border: 2px solid gray;
}

.carousel.is-fullscreen .carousel-close {
    /* show close button in fullscreen mode */
    display: block;
}