If you have a white bar between the tabs and the search area do the following: 1) type "about:profiles" in the search bar 2) Go to "Root Directory" and click on "Open Folder" next to the directory. 3) Create a folder named "chrome" in this directory 4) in that folder create a file named "userChrome.css". (make sure this is .css and not css.txt or something by enabling extensions for on windows (View, Options, Change Folder Options... , View , uncheck "Hide extensions for known file types" 5) Open the .css file with Notepad or any other text editor software of your choice 6) write the following in it: /* Remove Line at top of nav bar */ #nav-bar { box-shadow: none !important; } 7) Save and restart Firefox. If you still have the bar then: 1) Keep the files you created as they are 2) write about:config in the Firefox search bar 3) accept the risks 4) write "toolkit.legacyUserProfileCustomizations.stylesheets" in the search section. 5) Double click on "false" and set it to "True" If you have any other issues, let me know.