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Generic tools and helpers for building GDS front-end apps

Merge pull request #153 from quis/specify-node-sass-version

Add note to readme about incompatible Libsass versions
latest commit 65f8bcae83
David Singleton dsingleton authored

GOV.UK frontend toolkit

A collection of Sass and JavaScript files for using as part of your application's frontend.

This project is not tied to a specific language and is designed to be used as a dependency in as many different languages as needed.

There's a Gemfile and a package.json in this directory, but they are only for running tests and are not an indication that this project prefers Ruby or Node.js.


Ruby on Rails

We recommend you use the govuk_frontend_toolkit_gem and follow the installation instructions.


govuk_frontend_toolkit_npm is an NPM package that can be installed or included in your package.json.

If you are using a build tool that depends on Libsass then you may need to upgrade to a more recent version to use the grid helpers. Minimal compatible versions include node-sass 1.0.0, grunt-sass 0.16.0, gulp-sass 1.2.0 and libsass 3.0.0.


govuk_frontend_toolkit_composer is an composer package that can be added to your composer.json

Other projects

You can include the toolkit as a git submodule.

To add the submodule to your project run the following command substituting the path to a subdirectory in your project's assets directory:

$ git submodule add ./path/to/assets/govuk_frontend_toolkit

We recommend you use https rather than ssh for submodules as they don't require key exchanges when deploying to remote servers.

If you clone a project with the toolkit submodule installed you will need to initialise the submodule with the following command:

$ git submodule init

To update the toolkit to the latest version you can use:

$ git submodule update

Running tests

Tests for this project use Jasmine for the JavaScript and Ruby's scss and scss-lint to check the stylesheets.

The requirements are Node.js 0.8 or higher and PhantomJS, and Ruby:

bundle install
npm install
npm test

Using the local test runner

The test suite can be run by opening the ./spec/support/LocalTestRunner.html file in a browser for a more detailed trace of errors.

The files for unit tests and any supporting JavaScript should be added to ./spec/manifest.js file.


At the top of a Sass file in your project you should use an @import rule to include the file for the mixins you require, eg if you want the conditionals and typography mixins you should add:

@import '_conditionals';
@import '_typography';

You may need to include the relative path to the toolkit if it is installed as a submodule:

@import '../toolkit/_conditionals';

If you are compiling Sass from the command-line tool, here are some options we recommend.

In development:

sass --style expanded --line-numbers --load-path [path to]/govuk_frontend_toolkit/stylesheets input.scss output.css

In production:

sass --style compressed --load-path [path to]/govuk_frontend_toolkit/stylesheets input.scss output.css


Grid layout

Grid helpers to enable easy cross browser grids. The grids use absolute widths in older versions of IE or percentage based widths in modern browsers.

  • %site-width-container creates a 960px wide elastic container for you site content block
  • %grid-row container for a row of columns
  • @mixin grid-column($width, $full-width: tablet) a mixin to create grid columns of fraction width

These three grid helpers are designed to be used together and aren't guaranteed to work or behave in a predictable way if used in isolation.

There is also an %outdent-to-full-width selector which can be extended to outdent and element and cause it to take up the edge gutters and butt up to the edge of smaller screens.


#page-container {
  @extend %site-width-container;
.grid-row {
  @extend %grid-row;

  .column-third {
    @include grid-column( 1/3 );
  .column-two-thirds {
    @include grid-column( 2/3 );
.hero-image {
  @extend %outdent-to-full-width;

<div id="page-container">
  <div class="grid-row">
    <div class="column-two-thirds">
      Main content
    <div class="column-third">

  <div class="hero-image">
    <img ...>


Media query and IE helpers. These make producing responsive layouts and attaching IE specific styles to elements really easy.

To use the IE conditionals you will need to add extra stylesheets for each IE which look like:


$is-ie: true;
$ie-version: 6;

@import "application.scss";

Where application.scss is the name of your base stylesheet.



@mixin media($size: false, $max-width: false, $min-width: false)


note: the parameters are mutually exclusive and the first one found will be used.


size can be one of desktop, tablet, mobile. desktop and tablet should be used to add styles to a mobile first stylesheet. mobile should be used to add styles to a desktop first stylesheet.

It is recommended that you primarily use desktop for new stylesheets to enhance mobile first when serving to mobile devices.

$min-width $max-width

These should be set to an absolute pixel value. They will get added directly to their respective @media queries.


Styles that would normally be wrapped in @media queries by this mixin will be instead added to the main block if the $is-ie variable is true.

Setting $ignore-for-ie to true means those styles will not be added.

div.columns {
  border: 1px solid;

  @include media(desktop){
    width: 30%;
    float: left;
  @include media($min-width: 500px){
    width: 25%;
  @include media($max-width: 400px){
    width: 25%;


Conditially send CSS to IE browsers less than or equal to the named version.


@include ie-lte($version)



version is an integer value. Possible values are 6, 7, 8.

div.columns {
  border: 1px solid;

  @include ie-lte(7){
    border: 0;


Send CSS to a named IE version.


@include ie($version)



version is an integer value. Possible values are 6, 7, 8.

div.columns {
  border: 1px solid;

  @include ie(6){
    border: 0;


A collection of colour variables.

Departmental colours

  • $treasury
  • $cabinet-office
  • $department-for-education
  • $department-for-transport
  • $home-office
  • $department-of-health
  • $ministry-of-justice
  • $ministry-of-defence
  • $foreign-and-commonwealth-office
  • $department-for-communities-and-local-government
  • $department-for-energy-and-climate-change
  • $department-for-culture-media-and-sport
  • $department-for-environment-food-and-rural-affairs
  • $department-for-work-and-pensions
  • $department-for-business-innovation-and-skills
  • $department-for-international-development
  • $government-equalities-office
  • $attorney-generals-office
  • $scotland-office
  • $wales-office

Standard palette, colours

  • $purple
  • $purple-50
  • $purple-25
  • $mauve
  • $mauve-50
  • $mauve-25
  • $fuschia
  • $fuschia-50
  • $fuschia-25
  • $pink
  • $pink-50
  • $pink-25
  • $baby-pink
  • $baby-pink-50
  • $baby-pink-25
  • $red
  • $red-50
  • $red-25
  • $mellow-red
  • $mellow-red-50
  • $mellow-red-25
  • $orange
  • $orange-50
  • $orange-25
  • $brown
  • $brown-50
  • $brown-25
  • $yellow
  • $yellow-50
  • $yellow-25
  • $grass-green
  • $grass-green-50
  • $grass-green-25
  • $green
  • $green-50
  • $green-25
  • $turquoise
  • $turquoise-50
  • $turquoise-25
  • $light-blue
  • $light-blue-50
  • $light-blue-25

Standard palette, greys

  • $black
  • $grey-1
  • $grey-2
  • $grey-3
  • $grey-4
  • $white

Semantic colour names

  • $link-colour
  • $link-active-colour
  • $link-hover-colour
  • $link-visited-colour
  • $text-colour: $black
  • $secondary-text-colour
  • $border-colour
  • $panel-colour
  • $canvas-colour
  • $highlight-colour
  • $page-colour


.column {
  background: $green;


A collection of font-mixins. There are two different types of font mixins.

  1. Heading and Copy styles which are the font with added paddings to ensure a consistent baseline vertical grid.
  2. Core styles which are base font styles with no extra padding.

Heading and Copy styles

The following heading and copy styles exist:

  • heading-80
  • heading-48
  • heading-36
  • heading-27
  • heading-24
  • copy-19
  • copy-16
  • copy-14
h2 {
  @include heading-27;

Core styles

The following core styles exist:

  • core-80
  • core-48
  • core-36
  • core-27
  • core-24
  • core-19
  • core-16
  • core-14

@include core-[size]($line-height, $line-height-640)


$line-height and $line-height-640 are both optional. When used it is recomended to pass a fraction in for readability.

h1 {
  @include core-48;
h2 {
  @include core-24($line-height: (50/24), $line-height-640: (18/16));

Tabular numbers

Tabular numbers have numerals of a standard fixed width. As all numbers have the same width, sets of numbers may be more easily compared. We recommend using them where different numbers are likely to be compared, or where different numbers should line up with each other, eg in tables.

$tabular-numbers is an optional variable that may be passed to the heading, copy and core styles to use (or explicitly not use) tabular numbers. When no variable is passed, the default is non-tabular.

h1 {
  @include core-48;
h2 {
  @include core-24($tabular-numbers: true);

external links

external-link-default sets up the background image for all external links. This should be included on the default link style for a project.

After setting the default, apply includes from the following for different font sizes:

  • external-link-12
  • external-link-12-no-hover
  • external-link-13
  • external-link-13-no-hover
  • external-link-14
  • external-link-14-bold-no-hover
  • external-link-16
  • external-link-16-bold-no-hover
  • external-link-19
  • external-link-19-no-hover

external-link-heading is a unique style a background image for headings to groups of external links.

This uses the file-url helper which will by default output an image-url to be used with Compass or Rails Asset Pipeline, if you want to use a static path then set the $path variable to point to the public location of the toolkit image assets.


For a set style:

@include external-link-[style]

For a specific font size:

@include external-link-[size]-[weight]-[no-hover]


/* Default link style */
a[rel="external"] {
  @include external-link-default;
  @include external-link-19;

th.external-link {
  @include external-link-heading;

.inner a[rel="external"] {
  @include external-link-16;

.departments a[rel="external"] {
 @include external-link-16-bold-no-hover;


CSS3 helpers to abstract vendor prefixes.



@mixin border-radius($radius)


$radius a pixel value.

.column {
  @include border-radius(5px);



@mixin box-shadow($shadow)


$shadow a value set to pass into box-shadow.

.column {
  @include box-shadow(0 0 5px black);



@mixin translate($x, $y)


$x and $y are css values.

.column {
  @include translate(2px, 3px);


This can currently only handle linear top to bottom gradients.


@mixin gradient($from, $to)


$from and $to are colour values.

.column {
  @include gradient(#000, #fff);



@mixin transition($property, $duration, $function, $delay:0s)


Match up with the respective properties from transition.

.column {
  @include transition(left, 3s, ease);



@mixin box-sizing($type)


$type is one of border-box, content-box and padding-box.

.column {
  @include box-sizing(border-box);



@mixin calc($property, $calc)


$property the property to apply the calc to. $calc the calculation to.

.column {
  @include calc(width, "300% - 20px");


A mixin for creating buttons in the GOV.UK style.


@mixin button($colour)


$colour the background colour of the button (default is $green).

  @include button;
  @include button($grey-3);
  @include button($red);

The button text colour is set by the mixin to either light or dark, depending on the button background colour.

If you're applying these styles to non form elements, adding a class of 'disabled' to the element will emulate the disabled button style.

Phase banner

A mixin to create a GOV.UK Phase banner, with alpha/beta tag inside.


@mixin phase-banner($state)

$state is either alpha or beta.

$state sets the background colour of the phase tag to the appropriate alpha or beta colour.

Phase banner - Alpha
.phase-banner  {
  @include phase-banner(alpha);

<div class="phase-banner">
    <strong class="phase-tag">ALPHA</strong>
    <span>This is a new service – your <a href="#">feedback</a> will help us to improve it.</span>
Phase banner - Beta
.phase-banner  {
  @include phase-banner(beta);

<div class="phase-banner">
    <strong class="phase-tag">BETA</strong>
    <span>This is a new service – your <a href="#">feedback</a> will help us to improve it.</span>

Phase tags

A mixin to create an alpha/beta tag.


@mixin phase-tag($state)

$state is either alpha or beta.

$state sets the background colour of the phase tag to the appropriate alpha or beta colour.

Phase tag - Alpha
  @include phase-tag(alpha);
  Apply using the new service <span class="alpha-tag">ALPHA</span>
Phase tag - Beta
  @include phase-tag(beta);
  Apply using the new service <span class="beta-tag">BETA</span>


The gem also includes some JavaScript which by itself will have no effect on a page. It can be included with the asset_pipeline by adding the line:

//=require govuk_toolkit

Media player

There is a forked version of the Nomensa video player included and custom GOV.UK styles to be used with it. To use it you will need to include the script on your page and include the styles nested under an appropriate selector. For example:

@import "design-patterns/media-player";

.media-player {
  @include media-player;

You will also need to create your own initalizer to target the links you want to turn into videos. There are examples of how this works in the Nomensa Accesible Media Player repository.

Multivariate test framework

GOVUK.MultiVariateTest runs split tests to display different content, layouts etc to users.

It randomly assigns a user a cohort on first execution by setting a cookie, and on every execution sets a session level custom variable on Google Analytics to mark which cohort a user is in. This can be used to segment users in GA.

A simple content replacement test can be done by defining a set of cohorts with content. E.g.:

var test = new GOVUK.MultivariateTest({
  el: '.car-tax-button',
  name: 'car_tax_button_text',
  customVarIndex: 555,
  cohorts: {
    pay_your_car_tax: {html: "Pay Your Car Tax"},
    give_us_money: {html: "Give Us Money Or We Will Crush Your Car"}

A more complex test can be done by defining callbacks for what to do when a user is in each cohort:

var test = new GOVUK.MultivariateTest({
  name: 'car_tax_button_text',
  customVarIndex: 555,
  cohorts: {
    pay_your_car_tax: {callback: function() { ... }},
    give_us_money: {callback: function() { ... }}

If you want one cohort to appear 25% of the time then you can optionally weight that cohort:

var test = new GOVUK.MultivariateTest({
  name: 'car_tax_button_text',
  customVarIndex: 555,
  cohorts: {
    pay_your_car_tax: {weight: 25, callback: function() { ... }}, // 25%
    give_us_money:    {weight: 75, callback: function() { ... }}  // 75%

If you have a complex test, it may be worth extending MultivariateTest with your own. Callbacks can be strings which will call a method of that name on the current object.

Takes these options:

  • el: Element to run this test on (optional)
  • name: The name of the text (alphanumeric and underscores)
  • customVarIndex: The index of the custom variable in Google Analytics. GA only gives 50 integer slots to each account, and it is important that a unique integer is assigned to each test. Current contact for assigning a custom var slot for GOV.UK is: Ashraf Chohan
  • defaultWeight: Number of times each cohorts should appear in an array the random cohort is picked from, to be used in conjunction with weights on individual cohorts.
  • cohorts: An object that maps cohort name to an object that defines the cohort. Name must be same format as test name. Object contains keys (all optional):
    • html: HTML to fill element with when this cohort is picked.
    • callback: Function to call when this cohort is chosen. If it is a string, that method on the test object is called.
    • weight: Number of times this cohort should appear in an array the random cohort is picked from, defaults to the defaultWeight of the test.

Full documentation on how to design multivariate tests, use the data in GA and construct hypothesis tests is on its way soon.

Primary Links

GOVUK.PrimaryList hides elements in a list which don't have a supplied selector, they will then be shown when the user clicks. GOVUK.primaryLinks is a helper to add this behaviour to many elements.

Example markup:

<ul id="primary-list">
  <li class="primary-item">Item 1</li>
  <li>Item 2</li>
  <li>Item 3</li>

To add it to all lists which have items with the class primary-item use something like:


Or to add it just to that list you could use:

new GOVUK.PrimaryList($('#primary-list'), '.primary-item');

Stick at top when scrolling

GOVUK.stickAtTopWhenScrolling tries to add a class to an element when the top of that element would be scrolled out of the viewport.

The following would cause the element to stay when you scroll:

<div class="js-stick-at-top-when-scrolling">something</div>
.content-fixed {
  position: fixed;
  top: 0;
.shim {
  display: block;

If you also include the stopScrollingAtFooter JavaScript this will also try and stop the elements before they get to the bottom.

Selection buttons

Script to support a design of radio buttons and checkboxes requiring them to be wrapped in <label> tags:

  <input type="radio" name="size" value="medium" />

When the input is focused or its checked attribute is set, classes are added to their parent labels so their styling can show this.



To apply this behaviour to elements with the above HTML pattern, call the GOVUK.SelectionButtons constructor with their inputs:

var $buttons = $("label input[type='radio'], label input[type='checkbox']");
var selectionButtons = new GOVUK.SelectionButtons($buttons);

You can also call GOVUK.SelectionButtons with a selector:

var selectionButtons = new GOVUK.SelectionButtons("label input[type='radio'], label input[type='checkbox']");

This will bind all events to the document, meaning any changes to content (for example, by AJAX) will not effect the button's behaviour.

The classes that get added to the <label> tags can be passed in as options:

var $buttons = $("label input[type='radio'], label input[type='checkbox']");
var selectionButtons = new GOVUK.SelectionButtons($buttons, { focusedClass : 'selectable-focused', selectedClass : 'selectable-selected' });

var selectionButtons = new GOVUK.SelectionButtons("label input[type='radio'], label input[type='checkbox']", { focusedClass : 'selectable-focused', selectedClass : 'selectable-selected' });

destroy method

The returned instance object includes a destroy method to remove all events bound to either the elements or the document.

Using any of the selectionButtons objects created above, it can be called like so:


Deprecated functionality

The previous method of calling selection buttons is now deprecated. If you need to call them using this method, you will need to define this function:

GOVUK.selectionButtons = function (elms, opts) {
  new GOVUK.SelectionButtons(elms, opts);

This method will mean the destroy method is not available to call.


Released under the MIT Licence, a copy of which can be found in the file LICENCE.

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