I've tried to but everything feels just wrong.
Instead, I use garris.github.io/BackstopJS It uses three different browsers to render the result, take screenshots and then spots the diffs between each screenshot.
This tool does not check if padding: 10 is equal to padding: 10. Such test in CSS land is just wrong because of all the different layout engines we have in the web. Each browser and version interprets CSS differently. Each browser and version optimizes its rendering path differently. Each browser follows a different CSS spec implementation roadmap. That's why it makes no sense to me, to check and compare values of CSS code. Instead I check and compare the real rendered output.