.whatsapp-button {
  position: fixed;
  bottom: 20px;
  right: 20px;
  background-color: #25D366;
  color: white;
  border: none;
  border-radius: 50%;
  width: 60px;
  height: 60px;
  font-size: 30px;
  cursor: pointer;
  box-shadow: 2px 2px 6px rgba(0,0,0,.3);
  z-index: 999;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform .2s;
}
.whatsapp-button:hover { transform: scale(1.1); }