```css

.button {
  background-color: #66CC00;
  color: #fff;
}

.custom-amazon-popup-btn {
  background-color: #66CC00;       /* Greenpeace green */
  color: #fff;
  padding: 0.75em 2em;
  border: none;
  border-radius: 30px;
  font-weight: bold;
  font-size: 1.1rem;
  letter-spacing: 1px;
  cursor: pointer;
  transition: background 0.2s, color 0.2s;
  box-shadow: 0 2px 8px rgba(0,0,0,0.07);
}
.custom-amazon-popup-btn:hover,
.custom-amazon-popup-btn:focus {
  background-color: #7ee600;       /* light green */
  color: #fff;
  padding: 0.75em 2em;
  border: none;
  border-radius: 30px;
  font-weight: bold;
  font-size: 1.1rem;
  letter-spacing: 1px;
  cursor: pointer;
  transition: background 0.2s, color 0.2s;
  box-shadow: 0 2px 8px rgba(0,0,0,0.07);
}
```