Since your original problem was “It looks like my wordpress blog post are no longer separated into separate divs“, it would indicate that eacho post USED to be in a seperate, individual div, no?
Putting clear floats at the end of each posts may make look things good again, but that’s not the solution to your problem — it’s more like a workaround. Like @TheDoc says, the way to fix this is to wrap each post in its own div.
Anyways, I’m a bit confused cause I’m not really sure what it’s supposed to look like to be honest…
EDIT: If you add:
as the second line of code, and:
as the second-to-last line of code, each post would be wrapped in its own div already I think.