body {
    font-family: sans-serif;
    text-align: center;
}
ul {
    margin: 2em 0;
    padding: 0;
    font-size: 2em;
    list-style: none;
}
li {
    margin: 1em 0;
    padding: 0;
}
.animals {
    display: block;
    scroll-snap-type: y mandatory;
    height: calc(100vh - 6em);
    overflow: auto;
}

.animals section {
    display: flex;
    height: 100%;
    scroll-snap-align: start;
    flex-direction: column;
    align-items: center;
}
.animals section img {
    max-width: 100%;
    max-height: calc(100% - 4em);
}
.before-after {
    display: block;
    scroll-snap-type: y mandatory;
    height: calc(100vh - 6em);
    overflow: auto;
}
.before-after img {
    display: block;
    max-width: 100%;
    max-height: 100%;
    scroll-snap-align: start;
    margin: 0 auto;
}
/*    .before-after .after {
        display: none;
    }
    .before-after:hover .before {
        display: none;
    }
    .before-after:hover .after {
        display: block;
    }*/