2.1.2 #permalink Additional grid styles
grid-spacer adds a small padding to provide separation between grid elements.
grid-padder limits the width of a grid element to 80em (1280px in most browsers) so that the element won't be full-width at wide resolutions.
grid-lg-padder is the same, but has a limit of 64em (1024px at base zoom)
However it's not possible to display this behavior in the styleguide as these examples are forced into a 754px box...
Example
Markup
<div class="grid-12 grid-parent">
<div class="grid-12 grid-md-6 grid-lg-3 grid-spacer col_ggPrimary1"><div class="col_ggPrimary2"> </div></div>
<div class="grid-12 grid-md-6 grid-lg-3 grid-spacer col_ggPrimary1"><div class="col_ggPrimary2"> </div></div>
<div class="grid-12 grid-md-6 grid-lg-3 grid-spacer col_ggPrimary1"><div class="col_ggPrimary2"> </div></div>
<div class="grid-12 grid-md-6 grid-lg-3 grid-spacer col_ggPrimary1"><div class="col_ggPrimary2"> </div></div>
</div>
<br/>
<div class="grid-12 grid-parent col_ggPrimary1">
<div class="grid-12 grid-padder col_ggPrimary2"> </div>
</div>
<br/>
<div class="grid-12 grid-parent col_ggPrimary1">
<div class="grid-12 grid-lg-padder col_ggPrimary2"> </div>
</div>
Source:
layout/grid_gg.less, line 190