.part-container {
    width: 800px;
    margin: auto;
}

h1.part-title {

    border-bottom: solid 3px #012E40;
    width: 800px;
    margin-left: auto;
    margin-right: auto;

}

h2.section-title {
    text-align: center;
    border-bottom: solid 2px #012E40;
    width: 80%;
    margin-left: auto;
    margin-right: auto;
}

h3.subsection-title {
    text-align: center;
    border-bottom: solid 1px #012E40;
    width: 60%;
    margin-left: auto;
    margin-right: auto;
}