Jekyll + U.S. Web Design Standards

This is a Jekyll theme for the U.S. Web Design Standards.

Table of contents

1. Installation
   1. Development
   2. Versioning
2. Configuration
   1. Site title
   2. Navigation
   3. Page subnavigation
3. Assets
   1. Stylesheets
   2. Scripts
   3. Asset load order
4. Customization
   1. Customizing with Sass
   2. Customizing with CSS overrides
   3. Overriding includes and layouts
5. Components
   1. Header
   2. Footer
6. Layouts
   1. Base
   2. Docs
   3. Landing

Installation

1. Install the theme as a Ruby Gem by adding it to your Gemfile like so:

   gem 'uswds-jekyll', :git => 'https://github.com/18F/uswds-jekyll.git'

2. Fetch and update your bundled gems by running:

   bundle

3. Set the theme in your site's Jekyll configuration, _config.yml:

   theme: uswds-jekyll

You will need to restart your Jekyll server to see the effects.

Development

To develop this theme and/or test it locally:

1. Clone this repo

2. Run Jekyll (jekyll serve) in the local clone of this repo; or

3. Create a new Jekyll project, follow the installation instructions, then change your Gemfile to point at the local clone of this repo:

   gem 'uswds-jekyll', :path => '../path/to/uswds-jekyll'

Versioning

To reference a specific version of this plugin:

1. Visit the releases page and decide which version you want to use.

2. Add or update the :tag argument for this gem in your Gemfile to the name of the release tag, e.g.

   gem 'uswds-jekyll', \
     :git => 'https://github.com/18F/uswds-jekyll.git', \
     :tag => 'v0.1.1'

Configuration

Configuration of common elements (header, footer, navigation, etc.) happens in your project's data files. See this project's data directory for reference configurations of each component.

The base layout also provides a mechanism for automatically including stylesheets and scripts on a site-wide, layout-wide, and per-page basis. See asset load order for more information.

Site title

You can change your site's title with the title field in your _config.yml. If you want to provide an alternate title for use only in the site header, you can set the title field in _data/header.yml.

Navigation

This theme's navigation system is powerful and flexible. Named navigational lists live in your project's _data/navigation.yml, e.g.

# _data/navigation.yml
primary:
  - text: Documentation
    href: /docs/
  - text: Support
    href: /help/

  # link objects with a 'links' field will be presented as
  # collapsible link lists. The 'links' field can either be a
  # reference to another link list in this file, or a literal list.
  - text: Section title
    links: <links>

This scheme allows you to define navigational elements that can be shared by different components, such as the header and footer. See the documentation for those components for more info.

Page subnavigation

If you're using the docs layout, each page may declare its own side navigation and subnavigation in its front matter:

---
sidenav: documentation
subnav:
  - text: Section one
    href: '#section-one'
  - text: Section two
    href: '#section-two
---
## Section one

## Section two

As with the header and footer, the sidenav field may either reference a common navigation list from _data/navigation.yml (recommended) or be a literal list of links.

The subnav field should be used to link to sections within the current page, because links to other pages will cause the linking page's side navigation to collapse when visited.

Pro tip: Unless your Jekyll configuration specifies otherwise, the default Markdown formatter (Kramdown) will automatically generate predictable id attributes for your page headings and convert markdown like this:

## Section one

into:

<h2 id="section-one">Section one</h2>

If you're using Redcarpet, you will need to configure it to enable the with_toc_data extension in your _config.yml, like so:

markdown: redcarpet
redcarpet:
  extensions:
    - with_toc_data

Assets

The stylesheet and script includes each incorporate the Standards CSS and JS files if the corresponding styles and scripts lists aren't defined in your _config.yml. So unless you add one or both of those manually, your HTML will include the following:

<!-- in the <head> -->
<link rel="stylesheet" href="/assets/uswds/css/uswds.min.css" media="screen">
<!-- before </body> -->
<script src="/assets/uswds/js/uswds.min.js" async>

Read more about customizing stylesheets and scripts below.

Stylesheets

As a general rule, all stylesheets are inserted in a layouts' <head>, which qualifies them as "render-blocking". Site stylesheets can be specified in _config.yml or a layout or page's front matter YAML in the following form:

styles:
  - /path/to/sheet.css
  - href: /path/to/sheet.css
    media: (screen|print|all) # optional

Stylesheets specified as objects (in the latter item above) must have an href property. The media defaults to screen.

Scripts

As a general rule, all scripts are inserted before a layouts' </body>, which prevents them from blocking the rendering of your page's content. Scripts can be specified in _config.yml or a layout or page's front matter YAML in the following form:

scripts:
  - /path/to/script.js
  - href: /path/to/script.js
    async: true # optional

Scripts specified as objects (in the latter item above) must have a src property. Scripts with async: true will get an async attribute, which tells the browser not to let this script's loading block the execution of subsequent scripts. If the execution order of your scripts is not important, setting async: true may provide performance benefits to your users. (Conversely, if you don't know whether your scripts need to execute in a particular order, then you should not set async: true because it may prevent your scripts from running propertly.)

Asset load order

Both stylesheets and scripts can be configured

1. Assets configured at the site level (in your _config.yml) will be loaded in all pages that use the USWDS layouts.
2. Those configured at the layout level (in that layout's front matter) will be loaded on all pages that use that layout, after site assets.
3. Those configured at the page level (in the page's front matter) will be loaded last.

Customization

You have two options for customizing the CSS: Sass or CSS overrides. Individual sites can also selectively override individual includes and layouts.

Customizing with Sass

1. Create a Sass (or SCSS) entry point that sets variables and then imports the USWDS source files:

   ---
   # assets/main.scss
   ---
   // set your variables or @import them here.
   
   // at the very least, you should set the USWDS font and image paths
   // to the correct paths relative to assets/main.css, like so:
   $font-path: 'uswds/fonts';
   $image-path: 'uswds/img';
   
   @import 'uswds/all';

2. Change the path to your site's default stylesheet in your _config.yml:

   styles:
     - /assets/main.css

All of the Standards' SCSS source files are placed in the _sass/uswds directory and are available as Sass imports via @import 'uswds/<path>';. See the Jekyll docs for more information about its Sass/SCSS support, and configuring its Sass renderer in your site's config.

Customizing with CSS overrides

1. Create a new CSS or Sass file that defines your customizations, e.g.

   ---
   # assets/uswds-overrides.scss
   ---
   .usa-header {
     // overrides here
   }

2. Add the new stylesheet's path to your _config.yml after uswds.min.css:

   styles:
     - /assets/uswds/css/uswds.min.css
     - /assets/uswds-overrides.css

Overriding includes and layouts

Any include or layout can be overridden by your site by placing a file with the same name into your site's _includes or _layouts directory. For instance:

• To change how stylesheets are loaded or referenced, you can create your own _includes/styles.html, which will subsequently change how stylesheets are loaded in all layouts that inherit from the USWDS base layout.

• You can change how the side navigation is rendered (but not which data it receives) in the docs layout by creating your own _includes/sidenav.html.

• You can change how and whether the side navigation is displayed at all in the docs layout by overriding _layouts/docs.html.

Components

For some Standards components, there are two different files that control how data is passed to the template:

1. components/{component}.html is the low-level template that assumes a similarly named global template variable. For instance, the header component operates on the header template variable.
2. {component}.html is the "concrete" implementation of the component that sets the appropriate global variable then includes the low-level template.

This separation allows you to override either of the component includes in your own Jekyll site without having to re-implement either the high- or low-level logic. For instance, if you want your header data to come directly from the Jekyll configuration file (_config.yml) rather than _data/header.yml, you can override _includes/header.html to look like this:

{% assign header = site.header %}
{% include components/header.html %}

Header

The header.html include sets the header template variable to site.data.header, the value of which is set in your Jekyll project's _data/header.yml file. Then it includes components/header.html to render the header's markup.

See this repo's header.yml for more info.

Footer

The footer.html include sets the header template variable to site.data.footer, the value of which is set in your Jekyll project's _data/footer.yml file. Then it includes components/footer.html to render the footer's markup.

See this repo's footer.yml for more info.

Layouts

This theme provides the following layouts, which you can use by setting the layout front matter on each page, like so:

---
layout: name
---

layout: base

This is the bare-bones Standards layout, which does all of the basic page scaffolding then drops the page content into the <main> element. All of the other layouts "inherit" this one and provide other features in the content block.

The base layout provides a layout front matter hook to add attributes to the <main> element. You can see how this works in the docs layout.

layout: landing

This layout implements the landing page template, which accommodates the following front matter:

hero: # optional
  image: /path/to/image.jpg # optional
  callout:
    alt: Callout white text! # optional
    text: The rest of the callout
  button: # optional
    text: The button text
    href: /button-href/

# optional, but must be used in conjunction with 'intro', below
tagline: A tagline for your page
# also optional, but must be used with 'tagline', above
intro: |
  Some introductory text content.

  This will be processed as **Markdown**.

# an optional list of graphics to display before or after the content
graphics:
  - image:
      # note the indentation here: graphics[n].image.src
      src: /path/to/image.ext
      alt: optional alt text
    title: Optional graphic title, rendered as an <h3>
    description: Graphic description text, processed as _Markdown_.

# optional
graphics_position: (before|after)

Check out the YAML front matter in the landing demo page for an example of how to structure it.

layout: docs

This layout implements the document page template, and accommodates an optional side navigation. Supported front matter:

• sidenav is a key into _data/navigation.yml. See the navigation docs for more info.

  A page's "current" or "active" state in the sidenav is determined by whether a link's href matches page.url or page.permalink for each page being rendered.

• subnav is a list of links to display on this page under its own link in the side navigation.

  Note that subnav link hrefs are not prefixed with site.baseurl because this breaks hash links prefixed with #.

See the docs demo page for an example of how this works, and see _data/navigation.yml for how to structure named navigation data for your site.