body {
  background: #f4f6fa;
  font-family: 'Segoe UI', sans-serif;
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100vh;
  margin: 0;
}

.container {
  background: #fff;
  padding: 2em;
  border-radius: 12px;
  box-shadow: 0 6px 24px rgba(0, 0, 0, 0.1);
  text-align: center;
  max-width: 360px;
  width: 100%;
}

h2 {
  color: #333;
  margin-bottom: 20px;
}

canvas {
  margin: 10px 0;
  border: 1px solid #ccc;
  border-radius: 5px;
}

.input-group {
  display: flex;
  justify-content: center;
  gap: 10px;
  margin-bottom: 20px;
}

input[type="text"] {
  padding: 0.5em;
  font-size: 1em;
  width: 60%;
  border: 1px solid #aaa;
  border-radius: 6px;
}

button {
  padding: 0.5em 1em;
  border: none;
  background: #3182ce;
  color: white;
  font-weight: bold;
  border-radius: 6px;
  cursor: pointer;
  transition: background 0.3s ease;
}

button:hover {
  background: #225ea8;
}

button.submit {
  width: 100%;
  margin-top: 10px;
}

#msg {
  color: red;
  margin-top: 10px;
  font-weight: bold;
}