body {
  font-family: sans-serif;
  text-align: center;
  padding-top: 100px;
  background: #f4f4f4;
}

#sentence {
  font-size: 2em;
}

#toggle-btn {
  margin-top: 30px;
  width: 90px;
  height: 90px;
  border-radius: 50%;
  background: linear-gradient(145deg, #e60000, #990000);
  color: white;
  border: none;
  font-size: 16px;
  cursor: pointer;
  box-shadow: 0 6px 12px rgba(0, 0, 0, 0.3);
  transition: all 0.2s ease;
}

#toggle-btn:hover {
  background: linear-gradient(145deg, #ff1a1a, #cc0000);
  box-shadow: 0 8px 14px rgba(0, 0, 0, 0.4);
  transform: scale(1.05);
}

#toggle-btn:active {
  transform: scale(0.95);
  box-shadow: 0 3px 6px rgba(0, 0, 0, 0.2);
}