body {
  background-color: gray;
  overflow: hidden;
  margin: 0;
  justify-content: center;
  align-items: center;
  display: flex;
}

main{
  margin: 0;
  position: absolute;
  top: 50%;
  -ms-transform: translateY(-50%);
  transform: translateY(-50%);
}

canvas{
  width: 100% !important; 
  height: auto !important;
}