.whatsapp-float {
  position: fixed;
  bottom: 28px;
  left: 28px;
  z-index: 9999;
  background: #25d366;
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 56px;
  height: 56px;
  border-radius: 50%;
  box-shadow: 0 4px 24px rgba(37, 211, 102, .45);
  text-decoration: none;
  transition: transform .2s, box-shadow .2s;
}

.whatsapp-float:hover {
  transform: scale(1.08);
  box-shadow: 0 6px 32px rgba(37, 211, 102, .65);
}

@media (max-width: 640px) {
  .whatsapp-float {
    bottom: 18px;
    left: 18px;
    width: 52px;
    height: 52px;
  }
}