.avatar {
    width: 300px;
    height: 300px;
    margin: 0 auto;
    background-repeat: no-repeat;
    background-size: 300px;
    background-image: url('//www.gravatar.com/avatar/a518f17f430408ee83c582e890d6f269?s=300');
    box-shadow: 0 0 12px 12px black inset;    
}