It seems spacious in the vertical dimension, but I don't know how the individual menu item heights compare with the previous ones. Currently, I see (first screenshot):

Menus cannot be modified by normal add-ons, but they can be adjusted by applying custom style rules through a userChrome.css file. For example (second screenshot):

using:

/* Reduce height of bookmark menu items
     For optional Bookmarks Menu button menu */
#BMB_bookmarksPopup :-moz-any(menu, menuitem) { 
    min-height: 1em !important;
    padding-top: 2px !important;
    padding-bottom: 2px !important;
}
/* Reduce spacing around bookmark menu separators 
     For optional Bookmarks Menu button menu */
#BMB_bookmarksPopup menuseparator {
    margin-top: 2px !important;
    margin-bottom: 2px !important;
}

Is that the kind of thing you're looking for?

I've had a userChrome.css file for some years and this has enabled the bookmarks to be separated conveniently but, although I still have that file unchanged, the space between each has increased considerably. I've had some help with this but all that can be changed is to increase that spacing yet further; reducing the figure in that file makes no difference. It's definitely a problem arising from the latest version of Firefox because I have two computers that have begun to exhibit it since updating Firefox.

Could you please confirm the precise text of the userChrome.css file as it should be? Very many thanks.

Hi ahinton, the following is for the menu pictured in my earlier post. If that's not the menu you meant, where is the other menu?

When you have 10 minutes to focus on it, here's how to set up your rules:

This assumes you do not already have a userChrome.css file. If you do already have a working userChrome.css file, you just need to add the rule under (A) to your file.

(A) Select and copy the following style rule code

/* Reduce height of bookmark menu items
     For optional Bookmarks Menu button menu */
#BMB_bookmarksPopup :-moz-any(menu, menuitem) { 
    min-height: 1em !important;
    padding-top: 2px !important;
    padding-bottom: 2px !important;
}
/* Reduce spacing around bookmark menu separators 
     For optional Bookmarks Menu button menu */
#BMB_bookmarksPopup menuseparator {
    margin-top: 2px !important;
    margin-bottom: 2px !important;
}

(B) Generate and download a userChrome.css file

Open the following page and paste the above rules into the editor, replacing the sample rule:

https://www.userchrome.org/download-userchrome-css.html

Then click "Generate CSS File" and save the userChrome.css file to your computer. (See first attached screenshot)

Use the downloads list on the toolbar to open the downloads folder directly to the new userChrome.css file. (See second attached screenshot)

Minimize that Windows Explorer window for later reference.

(C) Create a new chrome folder in your profile folder

The following article has the detailed steps for that (#1, #2, and I recommend #3)

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

I have videos for both Windows and Mac in case the text is not clear.

(D) Move the userChrome.css file you generated in Step B into the chrome folder you created in Step C

The next time you exit Firefox and start it up again, it should discover that file and apply the rules.

See also:

• /questions/1237988 Spacing between bookbarks is broken with v.63 - userchrome.css does not work anymore - how to get it back?