I’m trying to revert to the old version without reinstalling an older version of Firefox. As per this question: https://support.mozilla.org/en-US/questions/1197929#answer-1068387 I have tried the following: about:config browser.tabs.remote.autostart = false browser.tabs.remote.autostart.2 = false That did not revert the responsive design to the old version. It did however prevent me from resizing the window because responsive design was only available for remote browser tabs. I then tried the following: 1. Type about:config in the browser's address bar and hit enter. 2. Right-click and select New > Boolean. 3. Name it browser.tabs.remote.force-enable. 4. Set its value to true. That simply allowed me to resize the window, but I was still stuck with the unusable new design. (Did you know you can’t type an apostrophe in these resized windows? And that is just one very tiny minor annoyance.) I then tried setting browser.tabs.remote.autostart to true and then back to false, and then setting browser.tabs.remote.autostart.2 to true and then back to false, then switching them up and then deleted the newly created Boolean. Then I pulled at my hair and cursed a plague upon the Mozilla developers, but none of it helped. My work requires me to interact with the responsive design for hours and hours a day and it is currently unworkable. Here are a few of the most annoying annoyances of the new design: 1: When you open two tabs and set them to responsive design, only the first tab will direct to a web page. The second will not. 2: Previously you could paste the dimensions of a resized page into the responsive design, but now you can only paste the first part of the dimensions and then have to manually type in the second. 3: Previously you could open a second tab and use a keyboard shortcut to resize the window to the same dimension. Now it reverts to some preset screen dimension, neither reflecting the other open tab or remembering the previous settings. 4: When using cntrl+F within the responsive design… well that’s just a whole seething hive of scum and villainy. 5: You cannot type an apostrophe on a webpage form in responsive design. WTF, why? (Actually many keystrokes will shoot the cursive off the page and into some mode I was too livid to take note of.) For the record, I am filled with loathing for this new design and can think of not one benefit it offers other than some designer gets to post it on their resume that they made a change to Mozilla. Anyway, insane ranting aside, any help that does not involve me having to figure out github would be much appreciated. Thanks in advance.