body {
  background-color: lightblue;
}
html,body {
margin:0;
padding:0;
overflow:hidden;
height: 100%;
width: 100%;
}
canvas {
height: 85vmin !important;
width:64vmin !important;
top: 50%;
left: 50%;
transform: translateX(-50%) translateY(-50%);
position: absolute;
}