.whatsapp_float{
    position: fixed;
    width: 60px;
    height: 60px;
    bottom: 40px;
    right: 40px;
    background-color: #25d366;
    color: #fff;
    border-radius: 50px;
    text-align: center;
    font-size: 50px;
    z-index: 100;
}
.whatsapp{
        margin-top: 16px;
    }
@media screen and (max-width: 767px) {  
    .whatsapp {
    margin-top:10px;
    }
    .whatsapp_float{
        width:40px;
        height:40px;
        bottom:20px;
        right: 10px;
        font-size:27px;
    }
}