I've upgraded our dev JBoss installation from 3.2.3 to 4.0.3SP1. One of the struts application is having a problem finding the CSS file, which is located in the jsp directory. It looks like the struts tag <html:base> is resolving differently between the 2 versions of JBoss.
On the app's web.xml, the welcome file is listed as:
<welcome-file-list> <welcome-file>jsp/logon.jsp</welcome-file> </welcome-file-list>