body {
  font-family: Arial, sans-serif;
  margin: 0; padding: 0;
  background: #f9f9f9; color: #333;
}
header {
  text-align: center;
  background: #4CAF50; color: white;
  padding: 1em 0;
}
main { padding: 1em; max-width: 600px; margin: auto; }
form { display: flex; flex-direction: column; gap: 1em; }
label { display: flex; justify-content: space-between; }
button { padding: 0.6em; background: #4CAF50; color: white; border: none; cursor: pointer; }
button:hover { background: #45a049; }
.overlay {
  position: fixed; top: 0; left: 0; width: 100%; height: 100%;
  background: rgba(0,0,0,0.8); display: flex; align-items: center; justify-content: center;
}
.gate-box {
  background: white; padding: 2em; border-radius: 8px; text-align: center;
}
.error { color: red; }