Change 98722 had a related patch set uploaded by Krinkle:
Install Grunt plugin for csslint

https://gerrit.wikimedia.org/r/98722

Change 98722 merged by jenkins-bot:
Install Grunt plugin for csslint

https://gerrit.wikimedia.org/r/98722

Change 98868 had a related patch set uploaded by Krinkle:
Create macro for csslint and use in oojs-ui and VisualEditor

https://gerrit.wikimedia.org/r/98868

Change 98868 merged by Krinkle:
Create macro for csslint and use in oojs-ui and VisualEditor

https://gerrit.wikimedia.org/r/98868

Does that also lint less or is there a extra tool?

This has been installed, deployed and is now also actively used by various projects.

In the main 'test' pipelines, however, this is no longer used as we have since migrated to using npm-test (from package.json) directly by installing it in a virtual machine in labs and executing it as specified by the source repository (instead of the install provided by Jenkins).

(In reply to comment #5)

Does that also lint less or is there a extra tool?

No, we don't yet use cssslint in mediawiki-core (current code doesn't pass) and neither does it validate LESS in any way.