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Column Setter

Column Setter is a Sass tool that lets you easily set up a custom responsive grid for your website and build a float- or flexbox-based layout that aligns to it. It uses one simple function and a small handful of optional mixins to generate CSS percentage widths based on your settings. And for the most part, it leaves the structure of your HTML and CSS entirely up to you.

Table of Contents


Begin by saving _column-settings.scss and _column-setter.scss in the same directory as your main Sass file.

In _column-settings.scss, customize your grid’s proportions by editing the values of the four variables at the top of the file ($mar, $col, $gut, $pad). These establish the spatial relationship between the grid’s various components. In the example below, gutters are twice the width of the padding, columns are twice the width of gutters, and margins are the same width as columns.

Since they represent flexible proportions rather than specific measurements, use only numbers for values, no units (e.g. 10, not 10px), and don’t delete any of these variables. For any you don’t need to use, just assign a value of 0.

$mar: 4; // Margin width
$col: 4; // Column width
$gut: 2; // Gutter width
$pad: 1; // Padding width

Next, customize the layout’s breakpoints by editing the $breakpoints map. You can define as many (or as few) breakpoints as you like, and name them whatever you want. Just be sure to:

  • use the syntax shown below
  • keep the breakpoints in order (smallest to largest)
  • include a name (e.g. xl), column count (cols, unitless) and minimum width (min-width, with units, such as em or px) for each breakpoint

All breakpoints use the same proportions specified in the variables above, but margin widths can be optionally customized for each breakpoint. Here’s a sample $breakpoints map with five breakpoints:

$breakpoints: (
  xs: ( cols:  4, min-width:  0,   margin: $pad ), // Includes optional custom margin
  sm: ( cols:  6, min-width: 30em, margin: $gut ), // Another optional custom margin
  md: ( cols:  8, min-width: 40em ),
  lg: ( cols: 12, min-width: 50em ),
  xl: ( cols: 16, min-width: 60em )


Once your settings are in place, import _column-settings.scss and _column-setter.scss (in that order) into your main Sass file:

@import "_column-settings.scss";
@import "_column-setter.scss";


To get the most out of Column Setter, using it in conjunction with * { box-sizing: border-box; } is strongly recommended. Column Setter is lean and mean, packing a lot of power into just one function and five optional mixins.


colspan() is a function used to generate percentage widths in proportion with the grid. To use it on an element, you’ll need to know how many columns wide the element’s container is. For example, to specify a width of six columns for an element inside a container that’s 12 columns wide:

.example {
  width: colspan( 6, 12 ); // 6 columns wide out of 12

The above code compiles to something like this:

.example {
  width: 48.82033%;

colspan() will also take the arguments p (padding) and g (gutter):

img.inset {
  float: left;
  width: colspan( 2, 8 );
  padding: colspan( p, 8 );
  margin-right: colspan( g, 8 );
  margin-bottom: colspan( g, 8 );

And for more granular control, you can combine colspan() functions:

.example {
  margin-left: colspan( 6, 12 ) + colspan( g, 12 );


grid() is a mixin used to establish the context for your grid. It sets the vertical margins for your layout at all breakpoints. The first (and only required) argument it takes is the class name of the layout’s container. If, for example, your layout is wrapped in a div with a class of main-content, you’ll invoke grid() like so:

@include grid( main-content );

This establishes the container’s horizontal margins for each of the breakpoints you specified in _column-settings.scss, and it compiles to something like this:

@media screen and (min-width: 0) {
  .content {
    margin: 0 3.38638%;
@media screen and (min-width: 30em) {
  .content {
    margin: 0 4.36194%;

You can also optionally include overlay as a second argument, which will put a translucent overlay of the grid on top of your layout so you can make sure everything is lining up correctly:

@include grid( main-content, overlay );

breakpoint-min(), breakpoint-max(), breakpoint-range()

The three breakpoint mixins generate media queries based on the $breakpoints settings specified in _column-settings.scss.

@include breakpoint-min( xs ) { ... }
@include breakpoint-max( sm ) { ... }
@include breakpoint-range( md, lg ) { ... }

The above code compiles to something like this:

@media screen and (min-width: 0) { ... }
@media screen and (max-width: 30em) { ... }
@media screen and (min-width: 40em) and (max-width: 50em) { ... }


full-width is a mixin used to break an element out of the layout and take up the full width of the viewport. It doesn’t take any arguments; its output is always the same. Use it like so:

.example {
  @include full-width;

The above code compiles to:

.example {
  width: auto;
  margin-left: calc(-50vw + 50%);
  margin-right: calc(-50vw + 50%);

Tips and tricks

  • For the most part, Column Setter code will compile even if you make a mistake—the invalid code will simply be ignored. If something isn’t working the way you expected, look for a WARNING on the command line. Column Setter can recognize common mistakes and help you troubleshoot them.

    WARNING: 'breakpoint-min(Gerald)' is invalid because 'Gerald' is not a valid breakpoint name. A 'breakpoint-min' mixin call must contain a valid breakpoint name, e.g. 'breakpoint-min(small)'. Current valid breakpoint names: xs, sm, md, lg, xl.
  • Elements are not confined to the width of their containers. Want an eight-column element inside a six-column container? No problem:

    width: colspan( 8, 6 );

    Want to center it? colspan() values can be made negative:

    margin-left: -( colspan( 1, 8 ) + colspan( g, 8 ) );
  • Each breakpoint is required to specify a column count, but those column counts don’t all have to be unique. You might want certain elements to change at a certain breakpoint without changing the rest of the layout. Just add another breakpoint in _column-settings.scss with the same number of columns as the one before or after it.

    $breakpoints: (
      small:  ( cols:  6, min-width:  0 ),
      medium: ( cols: 10, min-width: 30em ),
      large:  ( cols: 10, min-width: 35em )


Custom responsive grids in Sass that work in older browsers.





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