Did you publish any new content in between the time the blog was working correctly and the time you noticed the display issue? If so, you might have run into an "overflow" situation.
I've had that happen to me on several occasions. In some instances, it wasn't really an "overflow" (in that you could see all the text in the content block and it didn't appear to be hanging over the "edge" of the div) but it turned out that italicized text was causing the browser to think
it was past the edge.
Here's an article
that explains a bit more. Might or might not be applicable, but I offer the link just in case.
Good luck! Debugging stuff like this can be a bear.