A grid by @Guilh made with sass

SassGrid.css

.grid-1 {
  width: 6.5%;
}

.grid-2 {
  width: 15%;
}

.grid-3 {
  width: 23.5%;
}

.grid-4 {
  width: 32%;
}

.grid-5 {
  width: 40.5%;
}

.grid-6 {
  width: 49%;
}

.grid-7 {
  width: 57.5%;
}

.grid-8 {
  width: 66%;
}

.grid-9 {
  width: 74.5%;
}

.grid-10 {
  width: 83%;
}

.grid-11 {
  width: 91.5%;
}

.grid-12 {
  width: 100%;
}

SassGrid.scss

// ----
// Sass (v3.3.10)
// Compass (v1.0.0.alpha.20)
// ----

$col-width    : 65px;
	$gutter-width : 20px;
	$columns      : 12;

	@for $i from 1 through $columns {
			
		// Set container width relative to user variables
		$width: ($col-width * $columns) + ($gutter-width * ($columns - 1));

		// First, calculate grid size in pixels
		$grid: ($col-width * $i) + ($gutter-width * ($i - 1));

		// Then, calculate the responsive grid 
		$grid: ($grid / $width) * 100%;

    // Generate the grid classes
    .grid-#{$i} {
    	width: $grid;
    }
	}