The difficulty I had in building a selector that worked the way you specified was that I only needed to add a spacer line break after the last blocking element in any list item. If there were multiple blocking elements in the list item, the `$body.find(blockSepSelector).before(placeholderNode)` line above this code already adds line breaks between them. I couldn't find a way to get a selector to do this using the `+` operator.

I originally did have a selector that managed to accomplish that using the `:last-of-type` specifier in jQuery, but then I found out that the `:last-of-type` specifier isn't supported in IE, so I had to change my code to what it is now to get the same effect across all browsers.