html,
body {
  width: 100%;
  height: 100%;
  overflow: hidden;
  margin: 0;
  padding: 0;
  background: #f5f5f5;
  touch-action: manipulation;
  overscroll-behavior: contain;
  -webkit-user-select: none;
  user-select: none;
}

canvas {
  display: block;
  touch-action: none;
}

button {
  position: absolute;
  z-index: 1;
  top: 12px;
  left: 12px;
  min-height: 44px;
  padding: 0 14px;
  border: 1px solid #d8d8d8;
  border-radius: 4px;
  background: #fff;
  color: #111;
  font: inherit;
}