main {
    overflow: auto;
    padding-top: 2%;
    padding-bottom: 2%;
    padding-right: 2%;
}

.mosaic {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(25em, 1fr));
    grid-gap: 0.8em;
}

.mosaic.photos {
    grid-auto-rows: 14em;
}

.mosaic img {
    object-position: center;
    object-fit: cover;
    height: 100%;
    width: 100%;
    transition: filter 0.5s;
    filter: grayscale(0.8) brightness(0.4);
}

.mosaic img:hover {
    filter: none;
}

.mosaic .video {
    position: relative;
    width: 100%;
    height: 0;
    padding-bottom: 56.25%;           /* 9/16 */
}

.mosaic .video .yt {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}