Container classes

It would be nice if one could customize each container with CSS individually. Right now the only class being served is .forum-table-superheader. It would be good if each container would be assigned numerical value like it is done in subcontainers.

Example:
Main Container 1
--subcontainer 1
----forum
----forum
Main Container 2
--subcontainer 2
----forum
----forum

User cannot customize main container so 1 and 2 have for instance different background pictures.
Thanks