body, html {
  margin: 0;
  padding: 0;
  overflow: hidden;
  background: #000;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.controls {
  position: absolute;
  top: 20px;
  z-index: 10;
}

button {
  margin: 5px;
  padding: 10px 20px;
  font-size: 16px;
  cursor: pointer;
}

canvas {
  display: block;
}