html {
  height: 100%;
}
body {
  background-color: #000;
  overflow: hidden;
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0;
  padding: 0;
}
canvas {
  width: 800px;
  height: 800px;
  max-width: 90vw;
  max-height: 90vh;
  border: 3px solid #aaa;
  display: block;
}

@media (max-width: 768px) {
  canvas {
    width: 350px;
    height: 350px;
    max-width: 95vw;
    max-height: 70vh;
  }
}

@media (max-width: 480px) {
  canvas {
    width: 300px;
    height: 300px;
    max-width: 98vw;
    max-height: 60vh;
  }
}