_grid.styl

section, article, div, aside
	cf()

.span-half
	span(1/2)

.half
	col(1/2)

.third
	col(1/3)
	
.two-third
	col(2/3)

.quarter
	col(1/4)

.push-half
	col(1/2, offset:1/2)

.whole
	// col(1)
	center(mainWidth)

.medium-width
	center(800px)

.center-small
	center(500px)

.collapse
	+below(800px)
		col(1)