main.css

html, body {
    background-color: lightgrey;
    margin: 0;
    
}

.imageholder {
    position: absolute;
    margin: 10% auto;
    width: 100%;
    height: 60%;
    background-color: darkblue;
}

.centering {
    margin: 0 auto;
    width: 40%;
    height: 100%;
    background-color: black;
}