.whatsapp-button {
    position: fixed;
    z-index: 20;
    right: max(1.25rem, env(safe-area-inset-right));
    bottom: max(1.25rem, env(safe-area-inset-bottom));
    display: grid;
    width: 3.5rem;
    height: 3.5rem;
    place-items: center;
    border-radius: 50%;
    background: #25d366;
    color: #fff;
    box-shadow: 0 0.25rem 0.75rem rgb(0 0 0 / 25%);
    transition: background-color 160ms, transform 160ms;
  }

  .whatsapp-button:hover { background: #1eaa52; transform: translateY(-1px); }
  .whatsapp-button:focus-visible { outline-color: #fff; }
  .whatsapp-button svg { width: 1.9rem; height: 1.9rem; }

  @media (max-width: 600px) {
    .whatsapp-button {
      right: max(1rem, env(safe-area-inset-right));
      bottom: max(1rem, env(safe-area-inset-bottom));
    }
  }