Css questions

Hi folks! There are thing I don't understand with Css, seaside and pier. I created a MyLibrary that subclass WAFileLIbrary, I created the method myCss and selectorsToInclude that included myCss. I could successfully put styles in my pier application that were in MyLibrary. I also added my css images to that library. The questions are: 1) When I go to "edit design" command in Pier, all that Css I see, where it comes from ? I didn't see any Pier library that has those css. 2) When I edit design from Pier, where is it stored ? 3) When I add different libraries to a Application, how Css are inherit ? If I have defined different thing for a same class in different libraries for example, what happens ? 4) I really don't know when to add css to my library and when to add it to "edit design" command. 5) I tried to put some css in mylibrary, like .a:hoover .a: link .component but they are ignored. I guess it is using the css I see in "edit design". How can I do to override that css ? Ok, that's all for now. Thanks for the help. Mariano