SchwingSkin is CSS Grid framework especially for DotNetNuke. The idea is that you have one ore more base skin .ascx files that contain nothing more than the structure and DotNetNuke items like "ContentPanes" and "SkinObjects". You can style these using "Themelets" which are nothing more than CSS files.
You can download the first version here and play with and modify the themelets more documentation will soon be avaiable nokiko@gmail.com