body {
  font-family: Arial, sans-serif;
  padding: 20px;
  background: #f4f4f4;
}

h2 {
  color: #333;
}

input, button {
  margin: 10px 0;
  padding: 10px;
  width: 100%;
  max-width: 300px;
}

#certificate {
  border: 2px solid #333;
  padding: 20px;
  background: #fff;
}