html, body {
  margin: 0;
  background: black;
  overflow: hidden;
  touch-action: none;
}

canvas {
  display: block;
  margin: auto;
  background: #111;
}

.controls {
  position: fixed;
  bottom: 20px;
  width: 100%;
  display: flex;
  justify-content: space-around;
  z-index: 10;
}

.btn {
  width: 80px;
  height: 80px;
  background: #333;
  border: 2px solid #fff;
  border-radius: 50%;
  color: white;
  font-size: 20px;
  text-align: center;
  line-height: 80px;
  user-select: none;
}

.btn:active {
  background: #555;
}