body {
  font-family: Arial, sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
  background: #f5f5f5;
}
.container {
  background: #fff;
  padding: 2rem;
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
  text-align: center;
}
input {
  padding: 0.5rem;
  font-size: 1rem;
  width: 200px;
  margin-right: 0.5rem;
}
button {
  padding: 0.5rem 1rem;
  font-size: 1rem;
  border: none;
  border-radius: 4px;
  background: #3f51b5;
  color: #fff;
  cursor: pointer;
}
button:hover {
  background: #303f9f;
}
#result {
  margin-top: 1rem;
  font-size: 1.2rem;
  font-weight: bold;
}