|No such thing as a small change|
Why don't you post some example CSS to make it easier for people to try it out?
I turned those options on to see how well the CSS-based layout works and I can't actually do that since all it does is remove the structure that used to be there. I am not going to try to write CSS to try to restore the structure; my expectation is that I would spend no small amount of time and then would still fail. But that wouldn't prove anything other than my failure at CSS.
You surely already have some CSS. I'd love to see CSS that just restores the original structure (or nearly so). Other examples that demonstrate some small part of the flexibility CSS should offer the user would be nice as well.
Or perhaps there are others who have switched to "div mode" and could offer their CSS.
If some CSS comes out of this that seems considered to be a reasonable starting point, then it might be good to link to that from a "?" (help) superscript near those 'div' options on Display Settings. Or perhaps such CSS should be added to the site default CSS since it would just be ignored if you don't have those DIVs turned on.