This is a theme for Firefox Quantum to look like Firefox 3.
YOU MUST HAVE FIREFOX 57 to FIREFOX 88.0.1. WILL NOT WORK ON PROTON-ERA "ROUNDED TABS" FIREFOX BROWSERS (v89 AND UP) OR NON-QUANTUM FIREFOX BROWSERS (v56 OR LOWER)
Make sure you have toolkit.legacyUserProfileCustomizations.stylesheets ENABLED IN about:config.
Make sure Title Bar, Menu Bar, and Bookmarks Toolbar are enabled in Customize Toolbar. You also must add at least one bookmark to the Bookmarks Toolbar to keep it visible if you haven't enabled it before.
Optional: Enable the Search Bar and drag it to the right of Address Bar. Put Zoom Controls to the right of Search Bar. Enable Home Button and Reload button and place them like this: BACK - FORWARD - RELOAD - HOME
YOU MUST HAVE THIS BASIC ADDONS.MOZILLA.ORG THEME INSTALLED: Firefox 3 Classic by cg-realms You can get it at https://addons.mozilla.org/en-US/firefox/addon/firefox-3-classic/
Install the Stylus add-on and import the .json file in the repository. Then go to YouTube and enable all the styles from Stylus.
Install YouTube Redux and enable these:
Install Youtube - Right Side Description userscript from GreasyFork (google it) into Greasemonkey (an add-on for Firefox)
But I don't want the Menu Bar/Bookmarks Toolbar! Those are necessary prerequisites for this theme.
But Firefox 88 doesn't load websites nowadays! In about:config, create a string titled 'general.useragent.override' and set its value to the newest Firefox useragent.
Why doesn't this work on Firefox 89+? Firefox 89 completely changed the base UI. As a result, this theme is broken.
Why doesn't the YouTube theme work? Things change over time. I will try to keep the Youtube theme updated.
Youtube Redux isn't working/is broken! YouTube Redux does not get many updates nowadays. Things might be broken. I cannot control these as I do not develop the extension.