Gesso is a Sass-based starter theme that outputs accessible HTML5 markup. It uses a mobile-first responsive approach and leverages SMACSS to organize styles. This encourages a component-based approach to theming through the creation of discrete, reusable UI elements. Gesso is heavily integrated with Storybook and the Component Libraries module, allowing Drupal and Storybook to share the same markup.

Visit the Gesso Storybook demo site.

For more information, view the Gesso Drupal project page or Gesso GitHub repo. To submit bug reports or feature requests, visit the Gesso issue queue.

The following packages need to be installed on your system in order to compile and use Gesso.

• Node version 14.x.x or greater. Long-term stable recommended.

• npm version 7.x.x or greater.

1. Place the Gesso theme in your site’s theme directory. (e.g., themes/gesso) Read documentation on installing themes for more information.

2. Enable the Gesso Helper module. This module comes packaged with the theme, but must be manually enabled for the theme to function.

3. Install the Component Libraries module. Since many of the Drupal templates reference twig files inside Storybook using Twig namespaces, this module is required for the theme to function.

4. Install the Twig Tweak module.

5. Optional: Install the Twig Field Value module. This is not required, but it can make working with Twig templates easier. Please note, however, that using the |field_value Twig filter from this module will break Drupal’s QuickEdit functionality.

6. Optional: Install the Background Images Formatter module and its Responsive Background Images Formatter submodule. This is not required, but it will allow you to use images uploaded to Drupal as background images, with different image sizes at different breakpoints.

Because Gesso is a starter theme, you may want to rename the Gesso directory or copy its contents to a new custom theme directory based on the name of your project.

The easiest way to accomplish this is to use Drush. Type drush help gesso for more information. If you get an error that the gesso command is not defined, make sure you have enabled the Gesso Helper module.

If you can’t use Drush, then manually replace all instances of gesso within this directory with a machine-readable name of your choice, including folder names, filenames, and all occurrences within files. This custom name must start with a letter and may only contain lowercase letters, numbers, and underscores.

Edit the .info.yml file and update the theme name and description. You can also change the screenshot image (images/screenshot.png) shown on the Appearance admin page.

For development, you can set the theme up as part of a Drupal site or work only in Storybook. Gesso includes npm tasks to compile design tokens, CSS, JS, Storybook, and the SVG sprite using webpack.

To use these tasks, first run the following npm command in the theme folder to install node dependencies.

npm i

To compile the theme, start Storybook, and watch for changes run the following command in the theme directory:

npm run dev

Open localhost:6006 to view Storybook. If you’re using Docker (or some other container engine) for local development, this might be mapped to a custom domain or a port on a custom domain such as storybook.ddev.site or site.ddev.site:6006.

If you add new SCSS and/or JS files, you will need to restart webpack by canceling and then re-running npm run dev. New files will not be processed until webpack restarts. Errors will also be shown for duplicate filenames.

To initiate the build tasks only (without watching for changes), run the following command in the theme directory:

npm run build

Run npm run component to create boilerplate files for a new component. This is the recommended approach as it will set up basic Twig and Storybook files that you can modify.

Name your stories files [component].stories.jsx. See menu.stories.jsx for an example.

To match Storybook to your site’s branding, change the colors in .storybook/manager.js. Any fonts can be added in .storybook/manager-head.html. See the Storybook docs for more information about and examples of theming.

Sass can be compiled as part of the global styles.css file or to individual CSS files for use in a Drupal library.

@use is used to import Sass variables, mixins, and/or functions into individual SCSS files. @import is discouraged by the Sass team and will eventually be phased out.. This means that most files will start with @use '00-config' as *;. This allows you to use the design token accessor functions without an additional namespace. Other functions and mixins can be used similarly. Note that to avoid namespace collisions, only Gesso-related variables, mixins, and functions should be used with *.

All Sass files that are compiled to individual CSS files must have a unique filename, even if they are in different directories.

Prefix the name of your Sass file with _, e.g. _card.scss. Add it to the appropriate aggregate file (i.e. _components.scss).

DO NOT prefix the name of your Sass file with _, e.g. menu.scss. Import the config and global aggregate files. Import your SCSS file at the top of your Storybook file. See dropdown-menu.stories.jsx for an example. Don’t forget to add it to the gesso.libraries.yml file as well.

Stylelint and Prettier are used to lint CSS and SCSS files. Warnings will break the build, so if you have a valid reason to break Stylelint rules you can have it ignore code in two ways:

1. Add // stylelint-disable-next-line to the line just before where the Stylelint warning is triggered.

2. To ignore several lines, add // stylelint-disable before the code in question and add // stylelint-enable afterwards.

In both cases above, please add a comment about the valid reason to disable the Stylelint rule(s) in your use case.

The Stylelint rules can be changed in the .stylelintrc.yml file. By default, Gesso follows the sass-guideline.es and Prettier’s recommended guidelines, with some additional customizations.

The Prettier config can be changed in the .prettierrc file.

JavaScript can be compiled to individual JS files for use in a JavaScript library or included within a different JS file. JS files that use modern (ES2015+) syntax must be named [name].es6.js, but this is not required by the compiler. JavaScript files should go in the appropriate folder under source (e.g., source/03-components/menu for menu-related JavaScript). There is not a separate folder for JS files as there was in previous versions of Gesso.

All JavaScript files must have a unique filename, even if they are in different directories.

Prefix the name of your JavaScript file with _, e.g. _Menu.es6.js. Import it to the appropriate JavaScript file(s), (i.e. primary-menu.es6.js).

DO NOT prefix the name of your JS file with _. Import your JS file at the top of your Storybook file. See dropdown-menu.stories.jsx for an example. Don’t forget to add it to the gesso.libraries.yml file as well.

ESLint and Prettier are used to lint JavaScript files. If you have a valid reason to break one of the rules, you can ignore a specific line using any of the options in the ESLint documentation.

Please add a comment about the valid reason to disable the ESLint rule(s) in your use case.

The ESLint config can be changed in the .eslintrc.js file. Gesso follows the Airbnb standards, which are followed by Drupal as well.

The Prettier config can be changed in the .prettierrc file.

Gesso uses the configuration file source/00-config/config.design-tokens.yml to manage the theme’s design tokens. The npm build and dev tasks will automatically generate a global Sass map to easily pull design tokens into individual SCSS files.

The following Sass functions can be used to access the tokens defined in config.design-tokens.yml.

Output a shadow value from the box-shadow token list.

box-shadow: gesso-box-shadow(1);

Output a size value from the breakpoints token list.

@include breakpoint(gesso-breakpoint(desktop)) {
  display: flex;
}

@include breakpoint-max(gesso-breakpoint(mobile), true) {
  display: none;
}

@include breakpoint-min-max(
  gesso-breakpoint(mobile),
  gesso-breakpoint(tablet),
  true
) {
  display: block;
}

Output a color value from the palette brand token list.

color: gesso-brand(blue, light);

Output a color value from the colors token list.

color: gesso-color(text, primary);

Output a size value from the constrains token list.

max-width: gesso-constrain(sm);

Output a timing value from the transitions duration token list.

transition-duration: gesso-duration(short);

Output an easing value from the transitions ease token list.

transition-timing-function: gesso-easing(ease-in-out);

Output a stack value from the font-family token list.

font-family: gesso-font-family(primary);

Output a size value from the font-size token list.

font-size: rem(gesso-font-size(2));

Output a weight value from the font-weight token list.

font-weight: gesso-font-weight(semibold);

Output a color value from the palette grayscale token list.

color: gesso-grayscale(gray-2);

Output a height value from the line-height token list.

line-height: gesso-line-height(tight);

Output a size value from the spacing token list.

margin-bottom: rem(gesso-spacing(md));

Output an index value from the z-index token list.

z-index: gesso-z-index(modal);

The values in Gesso’s configuration file are also exported to JavaScript objects so that the same values can be used in CSS and JS. The JS objects can be found in source/00-config/_GESSO.es6.js. This file is also rebuilt whenever npm run dev or npm run build are run.

For example, to use a breakpoint in a script:

import { BREAKPOINTS } from '../../../00-config/_GESSO.es6';

if (window.matchMedia(`min-width: ${BREAKPOINTS.desktop}`).matches) {
  // Some script that should only run on larger screens.
}

This will use the same breakpoint as breakpoint(gesso-breakpoint(desktop)) in your Sass.

Gesso uses custom mixins to specify viewport width based media queries:

• breakpoint: min-width queries
• breakpoint-max: max-width queries
• breakpoint-min-max: queries with both a min and max width

Each mixin takes one or two width parameters, which can be a straight value (e.g., 800px, 40em) or a design token value called using the gesso-breakpoint function (e.g., gesso-breakpoint(tablet-lg)). The breakpoint-max and breakpoint-min-max mixins can also take an optional parameter to subtract one pixel from the max-width value, which can be useful when you want your query to go up to the value but not to include it, such as when using Gesso breakpoint token values.

Output a min-width based media query.

@include breakpoint(800px) {
  display: flex;
}

@include breakpoint(gesso-breakpoint(desktop)) {
  display: none;
}

Output a max-width based media query. The optional $subtract_1_from_max parameter will subtract 1px from the width value if set to true (default: false).

@include breakpoint-max(900px) {
  display: block;
}

@include breakpoint-max(gesso-breakpoint(mobile), true) {
  display: none;
}

Output a media query with both a min-width and max-width. The optional $subtract_1_from_max parameter will subtract 1px from the max-width value if set to true (default: false).

@include breakpoint-min-max(400px, 700px) {
  display: flex;
}

@include breakpoint-min-max(
  gesso-breakpoint(mobile),
  gesso-breakpoint(tablet),
  true
) {
  display: block;
}

A static Storybook site can be built with npm run build-storybook. You will then be able to view Storybook at YOUR_URL/themes/gesso/storybook/index.html.

Some aspects of Gesso can be configured in the theme settings. These include the Back to Top component, Breadcrumb options, and Button styles for links.

For the buttons, put the classes that should be added for each button size and button style on each line, with classes separated with ., similar to how you would add custom classes to the WYSIWYG editor.

c-button|Primary
c-button.c-button--secondary|Secondary
c-button.c-button--tertiary|Tertiary

To use these classes, select Gesso Button as the formatter for a link field under the entity's display settings.

Please use the Github issue queue https://github.com/forumone/gesso/issues for discussion, bug reports, feature requests, etc.

Submitted pull requests should be against the latest release candidate branch, such as 5.x-RC.

The Gesso theme is maintained by Corey Lafferty (@coreylafferty), KJ Monahan, and Dan Mouyard (@dcmouyard).