body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  background-color: #f0f0f0;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
}
.container {
  background-color: white;
  padding: 20px;
  border-radius: 8px;
  box-shadow: 0 0 10px rgba(0,0,0,0.1);
  text-align: center;
  max-width: 90%;
  width: 400px;
}
h1 { font-size: 24px; margin-bottom: 10px; }
p { font-size: 16px; margin-bottom: 20px; }
button {
  background-color: #5865F2;
  color: white;
  border: none;
  padding: 10px 20px;
  border-radius: 5px;
  font-size: 16px;
  cursor: pointer;
  margin: 10px 0;
}
button:hover { background-color: #4752C4; }
#keyDisplay { margin: 20px 0; }
#key { font-weight: bold; font-size: 18px; }
.hidden { display: none; }
@media (max-width: 600px) {
  h1 { font-size: 20px; }
  p, button { font-size: 14px; }
  .container { padding: 15px; }
}