.sm {
    display: inline-block;
    font-size: 40px;
    line-height: 60px;
    min-width: 60px;
    min-height: 60px;
    border-radius: 30px;
    margin: 5px;
    text-decoration: none;
    text-align: center;
    background-color: #63717A;
    color: #FFF;
}

.sm.fb:hover {
    background-color: #3b5998;
    color: #FFF;
}

.sm.tw:hover {
    background-color: #00ACED;
    color: #FFF;
}

.sm.ig:hover {
    background-color: #517FA4;
    color: #FFF;
}

.sm.yt:hover {
    background-color: #BB0000;
    color: #FFF;
}