WebExtension that imprement Sidebar into browser.
Chrome & Opera:
- Open chrome://extensions/
- Check "Developer mode"
- Click "Install unpacked extension" button
Firefox:
- Open about:debugging
- Click "Load Temporary Add-on"
Chrome: Removed by Google
Firefox: download
Opera: none yet
Chrome and Opera no idea
Firefox
- Create "chrome" folder inside your profile folder
- Create file "userChrome.css" inside "chrome" folder
- Copypaste "#TabsToolbar {visibility: collapse;}" info "userChrome.css"
- Restart Firefox
more tricks with "userChrome.css" here