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Stencil themes include an internal pattern library called Citadel, which consumes the ZURB Foundation framework. Foundation provides the basis for creating responsive themes. Citadel extends the Foundation framework’s mixins and components to provide Stencil’s own mixins, extensible components, and utilities.

Citadel Version

Citadel is based specifically on Foundation 5.5.3, which installs with the Stencil framework. We do not support Foundation 6.x, due to breaking changes introduced between versions 5.x and 6.x.

Citadel extends Foundation’s mix-ins and components to provide Stencil’s own mix-ins, extensible components, and utilities. These include drop-down lists, forms, and similar resources. Citadel resources are named according to BEM and SUIT CSS conventions. Classes are named functionally, rather than based on visual presentation or content. Our sass style guide explains more about how we name our classes. Citadel assets bundled with Cornerstone are located in these Cornerstone subdirectories:

  • cornerstone/assets/scss/settings/citadel/
  • cornerstone/assets/scss/components/citadel/

A theme developer might use drop-down lists, forms, and similar resources from Citadel’s design patterns. The design/style language underlying these Citadel resources is the Sass/SCSS preprocessor.

Components Directory

Citadel design patterns reside in the {theme-name}/assets/scss/components/ subdirectory. The components subdirectory contains the 4 following subdirectories:

  • /citadel/
  • /foundation/
  • /stencil/
  • /vendor/

You can see the components directory and its children present in the Cornerstone Theme Github Repository.

Citadel Subdirectory

The components/citadel subdirectory contains Citadel-specific resources. The resources are named according to our style guide, which follows BEM and SUIT CSS naming conventions: Class names are structured, and hyphens are meaningful (that is, hyphens are not used merely to separate words).

As a general rule, classes here are named functionally, not based on their visual presentation or their content. Here are some prototypes and examples:

  • componentName (for example: .dropdown or .buttonGroup)

  • componentName--modifierName (for example: .dropdown--dropUp or .button--primary)

  • componentName-descendantName (for example: .dropdown-item)

  • (for example:

  • u-utilityName (for example: .u-textTruncate)

  • Abstractly: [<namespace>-]<componentName>[--modifierName|-descendentName]

Components versus Utilities

Our naming scheme makes an architectural distinction between components and utilities. Components are defined as custom elements that enclose specific semantics, styling, and behavior. Our syntax for naming them is:


Component names are in camel case. We have tried to choose names that are as short as possible, but as long as necessary. For example:

  • .nav, not .navigation; but:
  • .button, not .btn

Utility classes are defined as low-level, structural and positional traits. Utilities can be applied directly to any element. Multiple utilities can be used together, and utilities can be used alongside component classes.

To make HTML patterns as reusable as possible, we have used utility classes sparingly, reserving them for component-level styling.

Our syntax for naming utilities is camel case, prefixed with a u- namespace:


Variables and Mixins

Citadel variables and mixins follow similar naming conventions.

Variables are things that can change over time. Their names are in camel case, and show context:

[<componentName>[--modifierName][-descendentName]-<propertyName> -<variablename>[--<modifierName>]

Mixins follow regular camel-case naming conventions. Namespacing is not universally required for mixins. However, where a mixin has been created for a utility, its name matches the utility’s name, including u- namespacing:

@mixin buttonVariant;
@mixin u-textTruncate;

Foundation Subdirectory

The /components/foundation/ subdirectory contains files installed by the ZURB Foundation framework. (Stencil’s Foundation support is limited to version 5.5.3.)

Stencil Subdirectory

The /components/stencil/ subdirectory contains CSS files unique to Stencil themes, which are used to create specific page elements within the themes. You can view this subdirectory and all its children in the Cornerstone Theme Github Repository.

This subdirectory’s children contain CSS for the following page elements.

Subdirectory UI Element/Purpose
account Customer account details
addressBox Customer shipping addresses
addReturn Add a product-return request
banners Banners displayed across storefront’s top and bottom
blocker Position .blocker element above another element, to prevent a user action
compare Layout for product-comparison table
facetedSearch Faceted-search toggle (on/off), navigation list, and filters
facetLabel Labels for faceted-search display
heroCarousel Carousel of prominent (“hero”) images
navPages Styles for page navigation, with responsive layout
navUser Styles for cart counter, quick search
productCarousel Carousel of product images
productReviews Styles for product reviews
productView Product display (with thumbnails suppressed for mobile/tablet), product details, product options (size, color, etc.), product sharing
quickView Quick-view modal window for a selected product
ribbon Top-right text badges, for messages like “On sale”
socialLinks Styles for social-media links
tags Styles for blog-post tags
toggleLink Styles for collapsible/expandable components
writeReview Styles for product-review submission form

Vendor Subdirectory

The /components/vendor/ subdirectory contains the consumed version of framework components from your chosen provider. There is some renaming of these components to match Stencil naming conventions.


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