```css
.custom-amazon-popup-btn {
  background-color: #00704A;       /* Greenpeace deep 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: #009963;       /* Lighter, energized green for hover */
  color: #f9f871;
  outline: none;
}
```