example scss - Grid

grid.scss

@mixin grid(
	$width: 960px,
	$gutter: 20px,
	$columns : 12,
	$prefix: true,
	$push: true
) {

	$column_width: $width/$columns;

	.grid {
		display: inline;
		float: left;
		margin-left: $gutter / 2;
		margin-right: $gutter / 2;
	}

	@for $i from 1 through $columns {
		.grid_#{$i} {
			@extend .grid;
			width: $i * $column_width - $gutter;
		}

		@if $prefix == true {
			.prefix_#{$i}{
				padding-left: $i * $column_width;
			}

			.suffix_#{$i}{
				padding-right: $i * $column_width;
			}
		}
	}
}