Spectre.css : Spectre.css is a lightweight, responsive and modern CSS framework for faster and extensible development.
lightweight and clean starting point for your...
Milligram : Milligram provides a minimal setup of styles for a fast and clean starting point. Just it! Only 2kb gzipped! It's not about a UI framework. Specially ...
Ink : A Responsive Email Framework from ZURB. Quickly create responsive HTML emails that work on any device & client. Even Outlook.
xCSS : xCSS bases on CSS and empowers a straightforward and object-oriented workflow when developing complex style cascades.
A set of small, responsive CSS modules that you can use in every web project.