body {
  font-family: "Segoe UI", "Microsoft Yahei", sans-serif;
  background: #f3f4f6;
  display: flex;
  justify-content: center;
  align-items: flex-start;
  padding: 40px;
}
.container {
  background: white;
  padding: 20px 30px;
  border-radius: 12px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.1);
  width: 960px;
  text-align: center;
}
.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: center;
  margin-bottom: 20px;
}
.controls label {
  font-size: 14px;
  background: #f8f9fa;
  padding: 6px 10px;
  border-radius: 8px;
}
button {
  background: #007bff;
  border: none;
  color: white;
  padding: 8px 14px;
  border-radius: 8px;
  cursor: pointer;
}
button:hover {
  background: #0056cc;
}
canvas {
  border: 1px solid #ccc;
  border-radius: 10px;
}