OK, thanks for the response.  I used the Install kit rather than the Upgrade kit (per the instructions from Mitchel Sellers' blog), but I'd expect that to have all the CSS fixes too.

I was hoping I'd be able to correct this before upgrading the production site, but I can't show you a page in test because it's on my laptop and isn't Internet facing.  I don't want to do extensive customization on DNN 4.6.2 because I only plan to stay there long enough to set up the upgrade to DNN 4.9.4; if I still have the issue in 4.9.4 I'll be doing some serious skin work.  Once I get my production site upgraded to 4.6.2 I'll post the URL here so you can look at it.  

Thanks for the suggestion - I'm afraid it didn't work.  How important is position in portal.css?  I tried it both at the end of the file, and right after the pane definitions, no luck either way. 

By the way, out of curiosity (since this worked with no effort on my part in 4.3.5 and 4.4.1), I compared the skin.css files from the install kits for 4.3.5 and 4.6.2 - the pane definitions are identical in both files and I didn't see a .DNNEmptyPane statement in either one.