Responsiveness Issues with 3.6 + a question about leads and sidebars

Since upgrading to 3.6, the responsiveness is all out of whack. The “lead” section becomes huge and everything else is tiny. Should I downgrade? Will there be problems with using an outdated version of wordpress?

Also, I used to be able to “fake” the dark section below the lead that you use on your home pages by adding some section/page breaks at the top of pages with sidebars and that is now disabled. Any idea how to correct that? Basically I’d like to be able to style other pages like the blog page is styled – Lead, dark section below lead, sidebar and content below that. Thanks!