.wtw-button {
    position: fixed;
    bottom: 20px;
    border-radius: 50%;
    display:flex;
    align-items:center;
    justify-content:center;
    box-shadow:0 5px 20px rgba(0,0,0,0.2);
    z-index:9999;
    animation: wtw-pulse 2s infinite;
    text-decoration:none;
}

.wtw-left { left:20px; }
.wtw-right { right:20px; }

.wtw-icon {
    width:50%;
    height:50%;
    background:white;
    mask: url('https://upload.wikimedia.org/wikipedia/commons/6/6b/WhatsApp.svg') no-repeat center;
    mask-size:contain;
    -webkit-mask: url('https://upload.wikimedia.org/wikipedia/commons/6/6b/WhatsApp.svg') no-repeat center;
    -webkit-mask-size:contain;
}

@keyframes wtw-pulse {
    0% { box-shadow: 0 0 0 0 rgba(37,211,102,0.7); }
    70% { box-shadow: 0 0 0 15px rgba(37,211,102,0); }
    100% { box-shadow: 0 0 0 0 rgba(37,211,102,0); }
}