CSS you using could be not applicable to html table elements. and panel built on div's. I guess that is the reason.
Thanks for your reply.
i tried to apply this css in html tables. It worked fine enough. But the problem is, They are not being applied to datatables. In firebug i can see those classes as applied to the element but i couln't get rounded corners.
I could not figure out any problem in the generated html from richfces