body {
    font-family: Nueue, Segoe UI, Arial, Tahoma;
}
.main-header {
    margin-top: 50px;
    margin-bottom: 70px;
}
.avatar {
    width: 100px;
    height: 100px;
    border-radius: 50%;
}
.center-text {
    text-align: center;
}
.center-block {
    margin: 0 auto;
    display: block;
}