- Install the Stylish plugin from here.
- Go to Tools > Addons > User Style > Install from URLs...
- Enter "https://raw.githubusercontent.com/maxmackie/powerline-mod/master/userChrome.css" in the popup.
- Profit
Seeing as browser and screen sizes are vastly different across multiple platforms, you may need to do some modifications of your own to the skin. This would include changing the margins and offsets to make everything look sexy.
powerline-mod is based off of the powerline style by Twily