html, body {
  margin: 0;
  padding: 0;
  height: 100%;
  background: #2b2d3a;
}
body {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
}
main {
  position: relative;
}
canvas {
  display: block;
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.4);
}