body {
    margin: 0px;
    height: 100vh;
    width: 100vw;
}

div.galleryitem {
    overflow: hidden;
    display: flex;
    float: left;
    width: 33%;
    height: 33%;
}

img {
    flex-grow: 1;
    object-fit: contain;
    width: 100%;
    height: auto;
    transition: 200ms;
    border-style: solid;
    border-width: 0px;
    border-color: white;
}

img:hover {
    border-width: 10px;
    border-radius: 20px;
    border-style: dashed;
    border-color: lightgray;
}