- Install Firefox.
- Install Sidebery.
- Download the "sidebery-data-###.json" and "userChrome.css" files from this repository.
- Open SideBery's settings and navigate to the "Help" section, click the "Import addon data" button and select the "sidebery-data-###.json" file.
- In Firefox's address bar, type "about:config". Search for "stylesheets" and double-click the "toolkit.legacyUserProfileCustomizations.stylesheets" field to toggle it to "true".
- In Firefox's address bar, type "about:profiles". For the profile currently in use, click "Open Folder" on the "Root Directory". Create a new folder named "chrome" inside the folder that opens, then paste the "userChrome.css" file into the "chrome" folder.
- Restart Firefox and everything should work!