Add a variable for the root directory.
Add a variable for the root directory.

This way, it can be easily overridden in other .less files.

alexjstubbs/ignition-dev,frafra/ProntoSoccorsoLiguria,alexjstubbs/ignition-dev,alexjstubbs/ignition-dev,thuongdoannguyen/thuongdoannguyen.github.io,alexjstubbs/ignition-dev,thuongdoannguyen/thuongdoannguyen.github.io,frafra/ProntoSoccorsoLiguria,thuongdoannguyen/thuongdoannguyen.github.io,alexjstubbs/ignition-dev