navbar - multi-page website with one org-mode file

Question

I'm generating multiple html pages from one org file. Function below generates html page for every heading level=1. I want to add simple navbar to every page.

Example content:

* home
** some heading
    this is home site
* about
** some heading
   this is about site

Function to modify:

(defun my-org-export-each-level-1-headline-to-html (&optional scope)
  (interactive)
  (org-map-entries
   (lambda ()
     (let* ((title (car (last (org-get-outline-path t))))
            (dir (file-name-directory buffer-file-name))
            (filename (concat dir title ".html")))
       (org-narrow-to-subtree)
       (org-html-export-as-html)
       (write-file filename)
       (kill-current-buffer)
       (widen)))
   "LEVEL=1" scope))

Example navbar:

<ul>
<li><a href="home.html">home</a></li>
<li><a href="about.html">about</a></li>
</ul>