body {
  font-family: 'Segoe UI', sans-serif;
  background: #f9f9f9;
  display: flex;
  height: 100vh;
  justify-content: center;
  align-items: center;
  margin: 0;
}
.container {
  background: white;
  padding: 30px;
  width: 360px;
  border-radius: 8px;
  box-shadow: 0 0 20px rgba(0,0,0,0.1);
}
input {
  width: 100%;
  padding: 10px;
  margin: 10px 0;
}
button {
  padding: 10px 20px;
  margin-right: 10px;
}
#message {
  margin-top: 10px;
  color: red;
}