body{
  width:100%;
  height:100%;
  padding:0;
  margin:0;  
}
canvas{
  display: block;
  margin-left: auto;
  margin-right: auto;
  position:absolute;
  margin: 0;
  top: 50%;
  left: 50%;
  -ms-transform: translate(-50%, -50%);
  transform: translate(-50%, -50%);
}