Currently Yii uses sections of the blueprint CSS framework.
We’re currently on 0.9 however a new version has finally come out which has some reasonably useful bug fixes that would be nice to incorporate.
Whilst most of the changes are minor there are some that work around some annoying issues that crop up for IE.
+1 Up.
Good point, I never did get around to adding this.
It’s now up at http://code.google.com/p/yii/issues/detail?id=1849
Edit: And it’s fixed! Will be in 1.1.6.
I see that blueprintcss has already been upgraded to the most recent version, 1.0.1 however I noticed a strange behavior in my YII app.
When looking at the screen.css file generated in the /assets/xxxxxxx/css subdirectory, the screen.css states, at its very top in the comment about section:
"Blueprint CSS Framework 0.9" ?! I am too new to yii to figure out why, maybe someone could sort this out for me?!
Seems i found the answer as well. It seems that Gii alone has been left behind.
The cached asset file is generated by /yii/framework/gii/assets/css/screen.css which apparently has not been upgraded to 1.x, maybe due to some incompatibilities, but it’s worth mentioning.
Those are not published, so first you need to figure out where that file comes from. 
Maybe you are using an extension which publishes it?
The Blueprint CSS is in document_root/css and/or in your themes directory (themes/classic/css)