Hey there! Let's break down how to get Firefox working in a single-page, tab-free (or nearly tab-free) setup for better focus and single-tasking. I'll cover both your core needs, plus which tools (Preferences, about:config, userChrome.css, extensions) fit each scenario.

If you just want Firefox to never open more than one page (replacing the current tab instead of creating new ones), you have two solid options:

Extensions (Easiest for Beginners) #

Search Firefox's Add-ons Store for extensions like Single Tab Mode or One Tab (no external links needed—just use the store's search bar). These tools automatically close extra tabs, force new links to replace your current tab, and some even let you "park" tabs temporarily if you need to switch later without cluttering your session.

• Pros: No technical setup, intuitive controls, easy to toggle on/off.

about:config Tweaks (No Extensions Needed) #

For a native solution without add-ons, tweak these hidden settings:

1. Open about:config in your address bar, accept the "This might void your warranty!" warning (it's safe for these changes).
2. Search for and modify these preferences:
   • browser.link.open_newwindow: Set to 1 (forces all new links to open in the current tab)
   • browser.link.open_newwindow.restriction: Set to 0 (ensures the above rule applies to all link types)
   • browser.tabs.loadDivertedInBackground: Set to false (external links will replace your current tab instead of opening in the background)

To eliminate tabs entirely (visually and functionally), you'll need a combination of about:config and userChrome.css, plus optional extension reinforcement.

Step 1: Lock Down Behavior with about:config #

Add these tweaks to the ones above to prevent tabs from ever being created:

• browser.tabs.closeWindowWithLastTab: Set to true (closes Firefox when you close the only tab, aligning with single-task logic)
• browser.tabs.hideTabBarWithOneTab: Set to true (hides the tab bar automatically when only one tab is open—this is a start, but we'll go further)

Step 2: Hide the Tab Bar Completely with userChrome.css #

To make the tab bar invisible even if a tab somehow slips through, use custom CSS:

1. First, enable custom styles in about:config:
   • Search for toolkit.legacyUserProfileCustomizations.stylesheets and set it to true
2. Locate your Firefox profile folder:
   • Open about:support, find the "Profile Folder" section, and click "Open Folder"
3. Create a chrome folder inside your profile folder (if it doesn't exist already)
4. Inside the chrome folder, create a file named userChrome.css and paste this code:

/* Fully hide the tab bar */
#TabsToolbar {
  visibility: collapse !important;
}

/* Keep window controls (minimize/maximize/close) visible */
#titlebar {
  visibility: visible !important;
}

5. Restart Firefox—your tab bar will be gone for good.

Step 3: Reinforce with an Extension (Optional) #

Add an extension like Tab Killer to automatically block any accidental tab creation attempts (e.g., if a website tries to open a new tab via JavaScript). This adds an extra layer of protection for your single-task workflow.

• Preferences: The native settings panel doesn't have direct tab-disabling options—you can only adjust basic link behavior, which isn't enough for either of your goals.
• about:config: Essential for controlling how tabs behave (preventing new tabs, closing the browser with the last tab). It's the backbone of both single-page and extreme tab-free modes.
• userChrome.css: The only way to visually eliminate the tab bar entirely. Without this, you'll still see a tab bar when a tab exists.
• Extensions: Great for beginners or if you want a toggleable solution. They can handle basic single-page mode and add extra safeguards for the extreme setup.

内容的提问来源于stack exchange，提问作者01AutoMonkey