Not at the current time. Can try using them this way : https://support.mozilla.org/en-US/kb/firefox-sidebar-access-bookmarks-history-social

Please let us know if this solved your issue or if need further assistance.

Unfortunately, extensions compatible with Firefox 57 cannot modify the appearance of the user interface in any significant ways.

However, someone who has a good idea of the aesthetic you're looking for could develop a custom style rule you could apply using a userChrome.css file.

A good site to ask about that is this "subreddit":

https://www.reddit.com/r/FirefoxCSS/

And I posted a general site about userChrome.css rules and examples of what they can do: https://www.userchrome.org/what-is-userchrome-css.html

If you get a great solution over there, could you post a link to it back here in case anyone else is looking for the same thing?