body { margin:0; padding:0; background: #323031;} /* to remove the top and left whitespace */

html, body { width:100%; height:100%; text-align: center;} /* just to be sure these are full screen*/

canvas { display:block; } /* To remove the scrollbars */

main {
  text-align: center;
}

canvas {
  margin-left: auto;
  margin-right: auto;
}