body {
  font-family: sans-serif;
  text-align: center;
  background: #f4f4f4;
  margin: 0;
  padding: 20px;
}

h1 {
  margin-bottom: 10px;
}

canvas {
  border: 2px solid #333;
  margin: 10px auto;
  display: block;
}

#result {
  font-size: 20px;
  margin-top: 10px;
}