html,
body {
  margin: 0;
  padding: 0;
}

body {
  height: 100vh;
}

#app {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100vw;
  height: 100vh;
  z-index: 10;
}

#app,
body > canvas {
  position: fixed;
  top: 0;
  left: 0;
}