Rated 4 out of 5 stars

Very good but do not work on local on domain with port like http://mywebsite.dev:8888/page

This review is for a previous version of the add-on ( 

Unable to reproduce

Hey Gagarine,

What version of Firefox do you use?
What version of Firebug do you use?
What version of Css Usage do you use?
What is your OS?
What is the error you are getting?
What does not work as you expected?