#wachat{
    position: fixed;
    bottom: 30px;
    right: 40px;
    width: 50px;
    height: 50px;
    -webkit-transition: All .5s ease;
    -moz-transition: All .5s ease;
    -o-transition: All .5s ease;
    -ms-transition: All .5s ease;
    transition: All .5s ease;
    z-index: 9999;
}

#wachat:hover{
    opacity: 0.8;
}



@media(max-width: 768px) {
    #wachat .btn-web{
        display: none;
    }
    #wachat{
        bottom: 20px;
        right: 20px;
    }
}
@media(min-width: 768px) {
    #wachat .btn-mobile{
        display: none;
    }
}