body{background:#fff}#app{background:#fff;overflow:auto;padding:12px}canvas{background:#ddd;background-image:linear-gradient(#fff 1px,transparent 0),linear-gradient(90deg,#fff 1px,transparent 0),linear-gradient(#000 1px,transparent 0),linear-gradient(90deg,#000 1px,transparent 0);background-size:20px 20px}