Galen Framework : Automated testing of look and feel for your responsive websites.
Layout testing seemed always a complex task. Galen Framework offers a simple solution...
Sizzy : A tool for developing responsive websites crazy-fast.
Open sourced : https://github.com/kitze/sizzy
This Is Responsive : Tips, Resources and Patterns for Responsive Web Design
Diagnostic.css : Diagnostic.css is a stylesheet which allows the user to test for common errors in a page's markup.
Also : https://github.com/karlgroves/diagnostic.css
Breaking CSS is easy. Checking every responsive page element is hard. That’s why there's BackstopJS.
