body {
  font-family: sans-serif;
  background: #f8f8f8;
  margin: 0;
  padding: 2rem;
}
.container {
  max-width: 500px;
  margin: auto;
  background: white;
  padding: 2rem;
  border-radius: 10px;
  box-shadow: 0 0 10px rgba(0,0,0,0.1);
}
label {
  display: block;
  margin: 1rem 0 0.5rem;
}
input, textarea, button {
  width: 100%;
  padding: 0.6rem;
  margin-top: 0.2rem;
}
canvas {
  margin-top: 1rem;
  display: block;
}