html, body {
    width: 100%;
    height: 100%;
    margin: 0;
    padding: 0;
}

.container {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.square {
    position: relative;
    width: 90vmin;
    box-sizing: border-box;
}

.square:after {
    content: "";
    display: block;
    padding-bottom: 100%;
}

.content {
    position: absolute;
    width: 100%;
    height: 100%;
}

#copyright-content {
    position: absolute;
    bottom: 0;
    right: 10px;
}