Compatible with Sprint 22 and above
Sorts css files with csscomb.js
Select css to sort and press
Ctrl + Shift + C or select
Edit > Sort with CSScomb in menu.
File > Extension Manager > Install from URL
Paste https://github.com/i-akhmadullin/brackets-csscomb into Extension URL field
Download zip and extract into arbitrary directory (or clone source files), then move the folder to the extensions folder (you can open this folder by clicking "Help > Show Extensions Folder" menu).