.btn-wsp {
    position: fixed;
    width: 65px;
    height: 60px;
    line-height: 0px;
    bottom: 50px;
    right: 50px;
    background: #25d366;
    color: #FFF;
    border-radius: 70px;
    text-align: center;
    font-size: 30px;
    box-shadow: 0px 1px 10px rgba(0, 0, 0, 0.3);
    z-index: 100;
    transition: all 300ms ease;
    animation: moveBg 1.5s infinite alternate;
}

/* Animación del fondo */
@keyframes moveBg {
    0% {
        background: #25d366;
    }
    50% {
        background: #128c7e;
    }
    100% {
        background: #25d366;
    }
}