.answer.hidden {
  display: none;
  margin-top: 10px;
  padding: 10px;
  background: #f0fdf4;
  border: 1px solid #bbf7d0;
  border-radius: 6px;
}
.answer {
  display: block;   /* default visible state */
  margin-top: 10px;
  padding: 10px;
  background: #f0fdf4;
  border: 1px solid #bbf7d0;
  border-radius: 6px;
}

.reveal-btn {
  margin-top: 10px;
  padding: 8px 14px;
  background: #2563eb;
  color: #fff;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  font-weight: bold;
}

.reveal-btn:hover {
  background: #1d4ed8;
}