footer {
    background-color: #1d1d1d; 
    font-size: 30px;
    padding: 20px 0; 
    margin-top: 150px; 
    border-top-left-radius: 20px; 
    border-top-right-radius: 20px; 
    margin-bottom: -8px;
    width: 100%;
    box-shadow: 0 4px 6px rgba(0,0,0,.2);  
}

a img {
    transition: .2s;
}

a img:hover {opacity: 30%;}