img {
    border-radius: 50%;
    width: 80vmin;
}

body, div {
    margin: 0;
    padding: 0;
}

.centred-image {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}

#overlay {
    position: absolute;
    margin-left: auto;
    margin-right: auto;
    left: 0;
    right: 0;
    text-align: center;
    color: white;
    text-shadow: 2px 2px 5px black;
    font-size: 300%;
}