There are two packages that provide syntax highlighting for Stylus in the Atom editor: Stylus and language-stylus.
The install numbers are quite different at 14,000 and 1,300, so I’m using Stylus which has overwhelmingly more installs.
Installing Stylus package
apm install Stylus
While Stylus is niche, it would be nice if it was prepared as an Atom Core Package by default.
That’s all from the Gemba.