Web Mail Interface problem after upgrade from R6.5 to R8.5

Dear all.

I had newly setup a Domino server R8.5 and replicated the old mails to it from an old Domino server R6.5. When I opened the mail through Web Browser, I found that the web mail interface was updated to R8.5’s styles. Is there any way I can change it back to the R6.5 view? Many thanks.