body {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
    text-align: center;
    line-height: 0;
    display: flex; 
    align-items: center; 
    justify-content: center;
    overflow: hidden;
}
canvas {
    width: 100%;
    height: 100%;
    position: absolute;
    margin:auto;
    left: 0;             
    right: 0;
    top: 0;
    bottom: 0;
}