See these search results for some examples for a multi-row Bookmarks Toolbar.

• https://support.mozilla.org/en-US/search/advanced?q=%22Multi-Row%20Bookmarks%22&asked_by=&answered_by=&w=2&a=1&sortby=1

Possible code you can try in userChrome.css

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */

/* Multi-Row Bookmarks Toolbar */
#PersonalToolbar {
  /* Override max-height */
  min-height: unset !important;
  max-height: unset !important;
}

#PersonalToolbar #PlacesToolbarItems {
  /* Override hiding */
  overflow-x: visible !important;
  overflow-y: visible !important;
  display: inline-block !important;
  padding-bottom: 1px;
}

#PersonalToolbar #PlacesToolbarItems .bookmark-item {
  /* Reduce padding to fit rows closer together */
  padding-top: 1px !important;
  padding-bottom: 1px !important;
}

It is not that difficult to create userChrome.css if you have never used it.

The first step is to open the "Help -> Troubleshooting Information" page and find the button to access the profile folder.

• https://support.mozilla.org/en-US/kb/use-troubleshooting-information-page-fix-firefox

You can find this button under the "Application Basics" section as "Profile Folder -> Open Folder". If you click this button then you open the profile folder in the Windows File Explorer. You need to create a folder with the name chrome in this folder (name is all lowercase). In the chrome folder you need to create a text file with the name userChrome.css (name is case sensitive). In this userChrome.css text file you paste the text posted. On Mac you can use the TextEdit utility to create the userChrome.css file as a plain text file.

In Windows saving the file is usually the only time things get more complicated because Windows can silently add a .txt file extension and you end up with a file named userChrome.css.txt. To avoid this you need to make sure to select "All files" in the dialog to save the file in the text editor using "Save File as".

You need to close (Quit/Exit) and restart Firefox when you create or modify the userChrome.css file.

See also:

• https://www.userchrome.org/what-is-userchrome-css.html
• https://www.userchrome.org/how-create-userchrome-css.html

In Firefox 69 and later you need to set this pref to true on the about:config page to enable userChrome.css and userContent.css in the chrome folder.

• toolkit.legacyUserProfileCustomizations.stylesheets = true
• https://www.userchrome.org/firefox-changes-userchrome-css.html

Thank you for this detailed response. Think I followed all instructions, but nothing has changed with bookmarks toolbar. It's still one row.

Don't understand the part below:

See also:

   https://www.userchrome.org/what-is-userchrome-css.html
   https://www.userchrome.org/how-create-userchrome-css.html 

In Firefox 69 and later you need to set this pref to true on the about:config page to enable userChrome.css and userContent.css in the chrome folder.

   toolkit.legacyUserProfileCustomizations.stylesheets = true
   https://www.userchrome.org/firefox-changes-userchrome-css.html

Were you able to create the userChrome.css file either with a plain text editor or via the www.userchrome.org website?

• https://www.userchrome.org/how-create-userchrome-css.html

Firefox blocks the userChrome.css file and you need to change a specific pref on the about:config page to make Firefox use this file.

• toolkit.legacyUserProfileCustomizations.stylesheets = true

You can open the about:config page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue.

• https://support.mozilla.org/en-US/kb/about-config-editor-firefox

Thank you so much!!!

Finally got it to work. There are now 5 rows of toolbar bookmarks. BTW, (just in case) is there a way to reduce it to only 2 or 3 rows?

What other cool stuff can we do to Firefox, with this command logic?

Thanks again! :)