html,
body {
  position: relative;
  height: 100%;
  overflow: hidden;
  width: 100%;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  margin: 0;
  padding: 0;
}

canvas {
  display: block;
}

#uiCanvas canvas {
  z-index: 888;
  position: absolute;
  top: 0;
  left: 0;
}

#drawingCanvas canvas {
  z-index: 999;
  position: absolute;
  top: 0;
  left: 0;
}