I guess you all know that there is a module specific class in DNN 5?
Any module gets a class "ModuleNameContent", so Reports will get the class ".DNN_ReportContent"
This would allow you to address all Reports modules or specific ones based on the pane they are in.
Lets say you want your text black, the text in all report modules blue, unless it's in a leftpane (there you want red);
.Normal{color:#000;}
.DNN_ReportContent .Normal{color:#00F;}
.LeftPane .DNN_ReportContent .Normal{color:#F00;}
Or let's say I want to address the reports module on the pages with page name "Work" and "PortFolio"?
Change the skin so it is contained in a div with this class:
<div class="MainContainer <%=PortalSettings.ActiveTab.TabName.ToLower%>">
...your skin...
</div>
Now you can address these modules by adding Page specific CSS to your skin.
.work .DNN_ReportContent .Normal, .portfolio.DNN_ReportContent .Normal {color:#F00;}
This is a "hard coded", but it can make things easier for admins if they don't have to change the container or skin.
(the "tolower" is to prevent problems if the page is named "WORK" for instance)