Disable Firefox 77 megabar and enable fullwidth UrlBar dropdown

1. Setup

1.1. Enable user profile stylesheets

Open Firefox configuration editor by typing about:config in the address bar and press Enter

At search preference name type-in toolkit.legacyUserProfileCustomizations.stylesheets and set the preference to true

1.2. Create chrome directory under your Firefox profile

Follow this guide to open your profile directory https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data or use default profile placement:

Operation System	Path
Windows	C:\Users<username>\AppData\Roaming\Mozilla\Firefox\Profiles\xxxxxxxx.default
macOS	Users//Library/Application Support/Firefox/Profiles/xxxxxxxx.default
Linux	/home//.mozilla/firefox/xxxxxxxx.default

1.3. Place userChrome.css to Firefox profile chrome folder

Download stylesheet

Operation System	Link
Windows	userChrome.css
Other	userChrome-linux-mac.css

Note: userChrome-linux-mac.css must be renamed to userChrome.css before placement to firefox-profile/chrome folder.

Done!

2. Possible preferences to change

Set browser.urlbar.openViewOnFocus to false at about:config for you want you address bar arrow back!