.whatsapp-fab {
  position: fixed;
  left: 20px;
  bottom: 20px;
  width: 62px;
  height: 62px;
  border-radius: 50%;
  background: #25D366;
  box-shadow: 0 8px 20px rgba(16,24,40,0.18);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  text-decoration: none;
  cursor: pointer;
  transition: transform .15s ease, box-shadow .15s ease, opacity .15s ease;
}
.whatsapp-fab:active { transform: scale(.98); }
.whatsapp-fab:focus { outline: 3px solid rgba(37,211,102,.25); }

@media (hover: hover) and (pointer: fine) {
  .whatsapp-fab:hover { transform: translateY(-4px); box-shadow: 0 14px 30px rgba(16,24,40,0.25); }
}
@media (max-width: 360px) {
  .whatsapp-fab { width: 56px; height: 56px; left: 14px; bottom: 14px; }
}