Incorporate media-queries from docs into core

[mahemoff]

I think some of the media queries in docs.css really be ought to be standard in every project, ie moved to the core. Specific examples.

Snippet 1

@media (min-width: 940px) {
  .nav-collapse.collapse {
    height: auto !important;
  }
}

Took me a while to figure out what was going on here. I collapsed the nav while in <940px (ie while the collapse toggle is visible), then extended the width and found the entire nav disappeared altogether! That's because .collapse has overflow: hidden set when collapsed, hence need height: auto as in the docs.

Snippet 2

@media (max-width: 768px) {
  body {
    padding-top: 0;
  }
}

Without this, I had a gap between the top of the page and the navbar (at <768px resolution), as I had a padding-top set for body (as in the nav).

Snippet 3?

This possibly applies to other media queries in the docs, particularly subnav-related. I haven't used subnav, so not sure.

[mdo]

Just added #1 to the main responsive file.

#2 is already in the responsive.less file, but targeted for max-width: 940px;.

The subnav is not part of the 2.0 release—we'll circle back around to that later.

Good feedback!