body {
    background: black;
}
#canvas1 {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 900px;
    height: 600px;
    border: 2px solid black;
    background: linear-gradient(to bottom, lightblue, darkblue, black);
    font-family: 'Orbitron', sans-serif;
}