How does this extension work?

[sdudnic]

Just installed the extension.

In the description any, any instruction, on how actually use it. How it is possible to write an extension, and just not describe how to use it?

Please, add a instruction on how to obtain the CSS differences, because it seems not really intuitive.

I see the CSS Diff in the Chrome developer tab, is white, nothing inside, I made all right click, left click, selected elements, but can't imagine how this work, and where are the differences.