body {
  font-family: Arial, sans-serif;
  text-align: center;
  padding-top: 100px;
  background-color: #f0f8ff;
}

button {
  padding: 15px 30px;
  margin: 20px;
  font-size: 18px;
  cursor: pointer;
}

.loader {
  border: 8px solid #f3f3f3;
  border-top: 8px solid #3498db;
  border-radius: 50%;
  width: 60px;
  height: 60px;
  animation: spin 1s linear infinite;
  margin: 40px auto;
}

.hidden {
  display: none;
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}