#goTop i {
    font-size: 2rem;
}
#goTop {
    position: fixed;
    width: 100px;
    margin-top: .3rem;
    margin-left: -50px;
    left: 50%;
    opacity: 0;
}
#goTop:hover {
    opacity: .9;
}

/*sm*/
@media (min-width: 576px) {
    #goTop {
        right: .3rem;
        left: auto;
    }
}
/*md*/
@media (min-width: 768px) {
    #goTop {
        margin-top: 5rem;
    }
}