body{
background-color: black;

}

canvas {/*https://stackoverflow.com/a/7782251*/
        padding: 0;
        margin: auto;
        display: block;
        width: 800px;
        height: 600px;
        position: absolute;
        top: 0;
        bottom: 0;
        left: 0;
        right: 0;
    }