.whatsapp-button {
    background-color: #25D366;
    border-radius: 50%;
    color: #fff;
    display: inline-block;
    font-size: 20px;
    line-height: 40px;
    text-align: center;
    text-decoration: none;
    width: 40px;
    height: 40px;
    position: fixed;
    bottom: 20px;
    right: 20px;
    z-index: 9999;
}