html,
body {
    padding: 0;
    margin: 0;
}
ul {
    padding: 0;
    margin: 0;
    list-style: none;
    display: flex;
    flex-wrap: wrap;
}

li {
    height: 40vh;
    flex-grow: 1;
}

img {
    max-height: 100%;
    min-width: 100%;
    object-fit: cover;
    vertical-align: bottom;
}