- Frameless design
- Ability to switch between workspaces and customize their color and icons
- Fold tabs into folders and other features that the Sidebery plugin provides.
- Install Sidebery Beta https://github.com/mbnuqw/sidebery
- Open Sidebery Setting and go to the Help section and click [Import Addon Data] (you should import this config sidebery-data.json )
- Download chrome folder ( https://github.com/yarikbright/Firefox-Arc-Style )
- Then paste Chrome folder to the C:\Users\ YOUR_NAME \AppData\Roaming\Mozilla\Firefox\Profiles\ (to the folder that contains [default-release] in the name)
- For left sidebar: https://github.com/SuperBo/Firefox-Arc-Style/tree/left-sidebar
Source: Reddit post