My Firefox customization

userChrome.css

/* 
Add this file under ~/.mozilla/firefox/***.default/chrome/ in linux
Or AppData/Roaming/Mozilla/Firefox/Profiles/***.default/chrome in windows

about:config --> toolkit.legacyUserProfileCustomizations.stylesheets
*/

/* Removes "Open All In Tabs" button in bookmarks tabs */
openintabs-menuseparator, .openintabs-menuitem, .bookmarks-actions-menuseparator {
   display: none !important;
} 


/* Bookmark tabs padding */
toolbarbutton.bookmark-item {
 padding: 6px !important;
}