Hide Firefox Tabs

This will hide the tabs while keeping the window control buttons accessible for Firefox on macOS.

1. Open your Firefox profile directory:

   • Go to about:profiles in the Firefox address bar.
   • Find your profile and click on "Open Folder".

2. Create a chrome folder in the profile directory if it doesn't exist.

3. Inside the chrome folder, create a file named userChrome.css.

4. Save the following CSS as userChrome.css and restart Firefox:

/* hides the native tabs */
#TabsToolbar {
  visibility: collapse;
}
/* leaves space for the window buttons on left */
#nav-bar > :first-child {
  margin-left: 68px;
}

/* Ensure the window controls are still visible on left */
#TabsToolbar .titlebar-buttonbox-container {
  visibility: visible !important;
  position: absolute !important;
  left: 0 !important;
  top: 0 !important;
  height: 100% !important;
}