In HTML5 output, you can set a parameter to include table-of-contents navigation in the
      <nav> element of each page. The navigation can be rendered in a sidebar or menu via
    CSS.
    About this task
      Earlier versions of DITA-OT used the TocJS transformation to render a JavaScript-based table of contents in an
        XHTML frameset for topic navigation. Recent toolkit versions provide a modern HTML5 navigation alternative.
      As of DITA-OT 2.2, the nav-toc parameter can be used in HTML5 transformations to embed
        navigation directly in topics using native HTML5 elements without JavaScript or framesets.
    
    Procedure
- 
        Set the nav-toc parameter to one of the following options:
        
          - The partial option creates a table of contents with the portion of the navigation
            hierarchy that contains the current topic (along with its parents, siblings and children).
- The full option embeds the complete navigation for the entire map in each
            topic.
 
- Optional: 
        Add custom CSS rules to style the navigation.
        
          For example, the DITA-OT documentation stylesheet includes the following rules to place the table of
            contents on the left side of the browser viewport and highlight the current topic in bold: 
            /* Style ToC nav as sidebar on desktop */
@media screen and (min-width: 992px) {
  nav.toc {
    float: left;
    width: 300px;
  }
}
nav.toc li.active > a {
  font-weight: var(--font-weight-bold);
}
 
 
 
Results
      Tip: For an example of HTML output generated using this method, see the HTML5 version of the DITA-OT
        documentation included in the installation folder under doc/index.html.