Style guide colours with Sass

Have you ever worked on a project and gone searching through design files for a reference to the brand colours? Ever seen numerous similar shades of a colour peppered throughout a codebase? If so, the project might benefit from a style guide.

I’ve just started a new job and before charging in to building the header, footer and homepage, I’ve created a page to demo all the base styles: typography, spacing, grid, form inputs and colours. As I build out a series of components for the site, those will be added too.

Colour swatches

In creating this guide, I came up with a nice technique for creating colour swatches using Sass map variables, loops, pseudo elements and interpolation - automatically outputting a series of classes along with the accompanying hex code for the color on the page.

The Problem

The big issue I’ve found with style guides is that they are often not kept up to date. Because of this, I wanted to make it as easy as possible to add a new colour swatch.

Create a mapping

Sass 3.3 has introduced the idea of a “map” variable - a bit like a Javascript object - allowing the ability to create a variable with a series of key:value pairs.

$map: (
	'key' : 'value',
	'otherKey' : 'otherValue'

In my project, I have a series of variables for all the commonly used colours: $color-brand for the main brand colour, $color-copy for the text, $color-link for links etc.

I created a map of these variables with a key that would be used in creating the modifier classes for each colour swatch.

$colours: (
	'brand'     : $color-brand,
	'copy'      : $color-copy,
	'link'      : $color-link,
	'hover'     : $color-hover,
	'highlight' : $color-highlight,
	'error'     : $color-error


The next step was to iterate over each of the items in the $colors map with a Sass @each loop, creating a series of classes with the correct background colour for each swatch.

.sg__colour {


@each $name, $color in $colours {

	.sg__colour--#{$name} {
// outputs 
// .sg__colour--brand { }
// .sg__colour--copy { }
// .sg__colour--link { }
// etc.

I’ve used the BEM naming convention here which I’ve just started experimenting with - perhaps the topic for a future post

Outputting the color code

I thought it would also be handy to output the color hex code beneath the swatch but I wanted this to be automated to avoid any chance of variable names and color codes getting out of sync.

Pseudo elements can be used to generate text content and this can be combined with Sass interpolation to output the value of a variable instead of using the variable in the code.

@each $name, $color in $colours {
	.sg__colour--#{$name} {
		&:after {
			content: "#{$color}";

This pseudo element can then be positioned beneath the swatch using position:absolute.

Colour swatches with hex output

And there you have it, an easy to maintain, Sassy colour swatch generator.

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