.container {
  margin: 0 auto;
  text-align: center;
  width: 380px;
}

input {
  margin: 5px;
  padding: 5px;
}

input#rule {
  width: 6em;
}

p {
  margin: 6px auto;
  font-size: 0.9em;
}

a,a:visited{
  color: #1199cc;
  text-decoration: none;
}

canvas {
  margin: 0 auto;
  display: block;
  border: 2px solid #ccc;
}