I’ve seen in many places before about vertical tabs in browsers, firstly Firefox with addons like tree-style tabs and similar ones and then Microsoft Edge added in the feature as well. I never really understood why it was so popular. My attention was recently drawn back to the topic by James Hackett (DistroByte) when he showed me his firefox config. I gave it a try using his css edits to make the vertical/tree-style tabs feel more native to Firefox and wow, I was missing out. Vertical tabs are extremely useful and a more efficient way of working with browser tabs.
First, they show more information, the tab titles aren’t squashed at the top of the screen when you have lots of tabs open (I may be guilty of that), instead, the titles are fully readable. In addition, the tabs that are opened from other tabs are nicely indented, making it very handy to see the origin of tabs.
Secondly, the tabs sidebar is collapsable, meaning when not open, it makes more screen real-estate available for the actual content of the website (especially useful for me on my 1366x768 screen laptop)

Okay, sold on vertical tabs? Let’s get it set up…

Steps to install:

  1. Open the about:config page in Firefox
  2. Search for toolkit.legacyUserProfileCustomizations.stylesheets and set it to True:
    • extremely useful for any userchrome customisation, not limited to vertical tabs
  3. Open the about:profiles page in Firefox
  4. Find the currently in-use profile (usually contains “default-release”) and open the root directory for that profile
  5. Make a new folder there called chrome (if it doesn’t already exist)
  6. Make a new file in that folder called userChrome.css and copy-paste this into it:
    /* [Hide](Hide) main tabs toolbar */
    #main-window[tabsintitlebar='true']:not([extradragspace='true']) #TabsToolbar > .toolbar-items {
      opacity: 0;
      pointer-events: none;
    #main-window:not([tabsintitlebar='true']) #TabsToolbar {
      visibility: collapse !important;
    /* Hide splitter, when using Tree Style Tab. */
    #sidebar-box[sidebarcommand='treestyletab_piro_sakura_ne_jp-sidebar-action'] + #sidebar-splitter {
      display: none !important;
    /* Hide sidebar header, when using Tree Style Tab. */
    #sidebar-box[sidebarcommand='treestyletab_piro_sakura_ne_jp-sidebar-action'] #sidebar-header {
      visibility: collapse;
    /* Adding empty space for buttons */
    #nav-bar {
      margin-right: 100px;
    /* 15px for dragging whole window by mouse*/
    #titlebar {
      appearance: none !important;
      height: 1px;
    /* Fix for main menu calling by Alt button */
    #titlebar > #toolbar-menubar {
      margin-top: 10px;
    /* Move minimize/restore/close buttons to empty space */
    #TabsToolbar > .titlebar-buttonbox-container {
      display: block;
      position: absolute;
      top: 5;
      right: 1px;
    /* If using titlebar/window manager, uncomment below */ 
    /* Remove empty space for buttons */
    /* #nav-bar { */
    /*   margin-right: 0 !important; */
    /* } */
  7. now go back into Firefox and install the Tree-Style Tabs extension:
    • this is fundamental for vertical tabs, you won’t have vertical tabs without this
  8. Restart Firefox, and 🎉 your regular tabs bar should have disappeared and have been replaced with the tabs sidebar
  9. You can toggle the tabs sidebar with F1 but I prefer ctrl + space to remap that:
    1. Go to about:addons in Firefox
    2. click the the little cog
    3. on the dropdown menu select Manage Extension Shortcuts
    4. Scroll down to Tree Style Tab, click on the box beside Toggle “Tree Style Tab” Sidebar and press ctrl + space to set your keyboard shortcut

Script to Auto-Install


Finished Product:

Firefox with Tree-Style Tabs

Further customisation:

I will have a follow-up post going into more detail about Firefox UserChrome customisation and theming.

Firefox with Tree-Style Tabs and DeepDark theme