I updated my firefox to the latest version :
Version 92.0
Now in Bookmarks Toolbar (Show more bookmarks) i have a problem about double Space between bookmarks.
There is a thread in stack like this :

This is really annoying.
Please guide me to fix this issue without manipulating or creating new rules in css.

CodePudding user response：

You have to create the file (and folder) yourself, and enable setting in about:config to tell Firefox it should apply it. Recycled howto for enabling and easy debugging from https://twitter.com/myfonj/status/1387584962354982912 :

How to inspect Firefox UI, make changes and persist them across restarts, in 9 steps:

1. Enable userChrome.css

Visit about:config, search for '.styles' and toggle toolkit.legacyUserProfileCustomizations.stylesheets to true.

2. Enable UI debugging

Open ≡ Menu > More Tools > Web Developer Tools > ⚙ Settings > Advanced and check (or press F12, then F1)

[✓] "Enable browser chrome and add-on debugging toolboxes"
[✓] "Enable remote debugging"

3. Obtain location of your Firefox user `<profile folder>`

See path at about:support#profile-row

4. Open Browser Toolbox

Launch ≡ Menu > More Tools > Browser Toolbox (or press Ctrl Shift Alt I)

5. Allow incoming connection.

6. Switch to Style(sheet) Editor.

7. Create new style

8. Try canonical `* { color: red !important; }`

9. Save it as `<profile folder>\chrome\userChrome.css`

(10.) Done. Now you can close the Toolbox and Firefox without losing your precious tweaks.