#main {
    display:flex;
    flex-direction:column;
}

.sub {
    max-width:75%;
    /* border-color:lightgrey;
    border-style:solid;
    border-width:.1em; */
}

.sub > p,ul {
    margin-left:5em;
}

.sub > h3 {
    border-bottom-color:grey;
    border-bottom-width: .1em;
    border-bottom-style:solid;
}