.main-title,
.sub-title,
.author {
    display: block;
    text-align: center;
    margin-bottom: 10px;
}
.main-title {
    font-weight: 700;
    font-size: 1.5em;
}

.sub-title {
    font-weight: 700;
    font-size: 1.2em;
}

.author {
    font-size: 1em;
    font-style: italic;
}