body {
    margin: auto;
    padding-right: 1em;
    padding-left: 1em;
    font: normal 1.1em monospace;
    max-width: 60em;
    text-align: justify;
}

.display-math {
    display: block;
    margin-top: 0.2em;
    margin-bottm: 0.2em;
    text-align: center;
}

.inline-math {
    display: inline;
}

a {
    color: inherit;
}

p {
    margin-bottom: 0
}

p + p {
    text-indent: 1.5em;
    margin-top: 0
}

nav#top-level {
    border-bottom: 1px solid grey;
    border-top: 1px solid grey;
    display: table;
    text-align: center;
    width: 100%;
}

nav#top-level ul {
    display: table-row;
}

nav#top-level ul li {
    display: table-cell;
}

nav#top-level ul li a {
    display: inline-block;
    width: 100%;
    text-align: center;
    text-decoration: none;
    color: inherit;
    text-transform: uppercase;
}

nav#top-level ul li a:hover {
    display: inline-block;
    width: 100%;
    text-align: center;
    background: lightgrey;
}