twbs/bootstrap — pull request #11983 by apotropaic (2013-12-22 21:21:07+00:00)
Title: added responsive layout utilities

These are useful in situations where you have a layout like at the top of the Narrow Jumbotron Template:

http://getbootstrap.com/examples/jumbotron-narrow/

If the navigation on the top right had the below `.pull-right-sm` it would be a normal block level item up to the sm breakpoint, preventing the 'Project Name' from awkwardly folding up and wrapping.