nav[role='doc-toc'] a {
    text-decoration: none;
}

nav[role='doc-toc'] a:hover {
    text-decoration: underline;
    background: yellow;
    color: red;
}

nav[role='doc-toc'] ul {
    list-style-type: none;
    margin-left: 1.5em;
    padding-left: 0;
}