body {
  background-color: rgb(30, 30, 30); /* or any color you want outside the canvas */
  margin: 0; /* optional, removes default margin */
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh; /* center canvas vertically and horizontally */
}

canvas {
  border: 5px solid black; /* black box border */
  background-color: #87CEEB; /* sky blue background INSIDE the canvas */
  display: block; /* remove inline gap */
}