body, html {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
    background: black;
    color: green;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: hidden;
}

canvas {
    position: absolute;
    top: 0;
    left: 0;
}