Add col-xs-offset-* shim to Bootstrap 3 for the mobile (xs) display responsive column offsetting that does not exist in the standard Bootstrap CSS.

bootstrap-3-xs-offset-shim.css

/*

  Include this after bootstrap.css
  
  Add a class of 'col-xs-offset-*' and 
  if you want to disable the offset at a larger size add in 'col-*-offset-0'
  
  Examples:
  All display sizes (xs,sm,md,lg) have an offset of 1
  <div class="col-xs-11 col-xs-offset-1 col-sm-3">
  
  xs has an offset of 1
  <div class="col-xs-11 col-xs-offset-1 col-sm-offset-0 col-sm-3">
  
  xs and sm have an offset of 1
  <div class="col-xs-11 col-xs-offset-1 col-md-offset-0 col-sm-3">
  
  xs, sm and md will have an offset of 1
  <div class="col-xs-11 col-xs-offset-1 col-lg-offset-0 col-sm-3">

*/

.col-xs-offset-12 {
	margin-left: 100%;
}
.col-xs-offset-11 {
	margin-left: 91.66666666666666%;
}
.col-xs-offset-10 {
	margin-left: 83.33333333333334%;
}
.col-xs-offset-9 {
	margin-left: 75%;
}
.col-xs-offset-8 {
	margin-left: 66.66666666666666%;
}
.col-xs-offset-7 {
	margin-left: 58.333333333333336%;
}
.col-xs-offset-6 {
	margin-left: 50%;
}
.col-xs-offset-5 {
	margin-left: 41.66666666666667%;
}
.col-xs-offset-4 {
	margin-left: 33.33333333333333%;
}
.col-xs-offset-3 {
	margin-left: 25%;
}
.col-xs-offset-2 {
	margin-left: 16.666666666666664%;
}
.col-xs-offset-1 {
	margin-left: 8.333333333333332%;
}
.col-xs-offset-0 {
	margin-left: 0;
}

/* Ensure that all of the zero offsets are available - recent SASS version did not include .col-sm-offset-0 */
@media (min-width: 768px) {
	.col-sm-offset-0,
	.col-md-offset-0,
	.col-lg-offset-0 {
		margin-left: 0;
	}
}

This is no longer needed since Bootstrap 3 later added this functionality.