body {
  margin: 0;
  overflow: hidden;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  width: 100vw;
  box-sizing: border-box;
}

main {
  position: relative;
  width: 100%;
  height: 100%;
}

canvas {
  position: absolute;
  transform: translate(-50%, -50%);
  left: 50%;
  top: 50%;
}