twbs/bootstrap — pull request #9669 by erikflowers (2013-08-16 04:36:22+00:00)
Title: - Added a new mixin to create a column for the base mobile widths, which...

- Added a new mixin to create a column for the base mobile widths, which allows for a class to use a "make-column()" so classes that don't use column sizes still get the padding, position, min-height. When using HTML classes that rely on the mixins to generate the columns, if you have a class that generates columns with a standard .make-*-column(*) within a media query, there is nothing on the base class to tell it to grab the base styles, as referenced in the grid.less line 16 "// Common styles for small and large grid columns".

this make-column() mixin essentially says to make the class a column, but since it's for a mobile 100% width it doesn't need any column variable since if you did want a column at the smallest size, you would use make-xs-column(*).