body {
  font-size: 1.5rem;
}

#canvas1 {
  border: 1px solid #000;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 500px;
  height: 500px;
}

@media (max-width: 540px) {
  #canvas1 {
    width: 250px;
    height: 250px;
  }
}
.controls {
  position: absolute;
  z-index: 1;
  top: 3rem;
  left: 50%;
  transform: translateX(-50%);
}