.whatsapp-btn {
    position: fixed;
    bottom: 20px;
    left: 20px;
    background-color: #25D366;
    color: white;
    width: 60px;
    height: 60px;
    border-radius: 50%;
    text-align: center;
    font-size: 30px;
    box-shadow: 2px 2px 3px #999;
    z-index: 100;
}

.whatsapp-btn i {
    margin-top: 15px;
}