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Drupal 8 Theme

The files contained in this repo provide a starting point for developing a Drupal 8 theme. It is a subtheme of Classy.

Consider this a work in progress. There is much that needs to be added and finished. (See the TODO list here.)

There are many concepts at play here to allow you to create a custom theme using tools for performance, accessibility, testing, and fast development.

This repo includes:

  • Gulp for task-running
  • Sass for pre-processing CSS, using Libsass so we don't get bogged down with Ruby
  • Browser Sync for simultaneous testing on multiple browsers
  • Image Optimization for minifying PNG, JPEG, GIF and SVG images on the fly
  • Bourbon Sass mixin library
  • Neat for semantic grids that are designed to work with Bourbon
  • Pattern Lab for designing in the browser and creating a living styleguide
  • And much more theme development goodness

Pre-installation Notes

The installation steps below presume you have already installed Drush, Node.js and npm on your system. If you have never used those before or are certain if they are available on your system, follow these installation instructions. Otherwise, you can skip to the installation instructions below.

Installation Instructions

We are assuming here you have already installed Drupal 8 and it is running on your development server. To begin installing this theme, navigate to the themes directory (cd themes). If you wish, you can add a new directory for your custom themes (mkdir custom && cd custom).

Where you see in these instructions your_theme you should substitute the name of your theme, using all lower case and with no spaces. Use underscores to separate words.

Now install the theme files using:

git clone your_theme

Change directories to where your put your theme.

cd your_theme

Rename the theme info.yml file.


Edit to reflect your theme's name and other details. Make sure you change the path under "# Locate files" to reflect your theme directory's name. See also "Defining a theme with an .info.yml file".

Rename the .theme file.

mv drupal8_theme.theme your_theme.theme

Edit your_theme.theme to reflect your theme's name in the provided preprocess function. Add more conditional logic and data (pre)processing of the output here as needed.

Rename the breakpoints.yml file.

mv drupal8_theme.breakpoints.yml your_theme.breakpoints.yml

Edit your_theme.breakpoints.yml by changing drupal8_theme to your_theme. This appears in three places. You should also remove, add or edit breakpoints as needed for your theme layout. At least for now, this will get you started.

Rename the libraries.yml file.

mv drupal8_theme.libraries.yml your_theme.libraries.yml

Editing may not be needed in your_theme.libraries.yml, or at least not right away. This is where you can add other CSS and JS files. You can find more information on the use of the libraries.yml file [here] (

Edit line 1 of gulpfile.js, replacing your-site.tld with the domain of your local site.

Now install all of the Node.js modules we need. (This will take a while.)

npm install

Finally, set up Pattern Lab.

gulp generate-pattern-lab

You're now ready to visit your Drupal site and enable the new theme.

Post-installation Notes

Running npm install and gulp install will add several files in directories called node_modules. The .gitignore file in your theme will prevent these files from being added to your repo. This is intentional because the files are only needed for development.

If you are adding developers on a team who are editing the theme, after they have cloned your site's repo they will need to navigate to the theme directory and run these commands:

npm install

As well as either

gulp generate-pattern-lab


gulp build-dev

Using PatternLab

To set patterns, follow instructions provided here.

The CSS files for Pattern Lab patterns are provided by your Drupal theme. This allows you to write once, yet use the same styling in the theme and in Pattern Lab. The CSS is provided by Sass (SCSS) and is automatically rendered using Libsass.

For development

The development of a theme using these files and configuation would normally proceed as follows:

  1. Design in the browser using pattern files in Pattern Lab. Ideally, you are creating patterns using markup that matches your Drupal markup so that your CSS provides the exact same styling. In the solution provided here, the Pattern Lab files are based on Twig, the same theming engine used in Drupal 8.

  2. Edit Sass files to provide layout and styling. As noted before Sass files are written once and used in Pattern Lab to largely eliminate redundant coding. The Sass files reside in your theme directory tree.

  3. Use Gulp commands to automate the development process. Before you beging writing files, use the command gulp build-dev to start up the full task-running process. Gulp will watch for file changes, process Sass files into CSS, trigger Drush to clear cache when Drupal template files are changed, and refresh the browser.

  4. By using gulp build-dev, your Drupal site and Pattern Lab will automatically launch in your default browser with Browser Sync. You will find the site at "http://localhost:3000." If the site fails to load and you see a message saying "The website encountered an unexpected error. Please try again later," don't panic. Try refreshing the browser manually. This problem sometimes occurs when the build process gets out of sync.

  5. Pattern Lab resides within the theme. The pages are always available for viewing from any server running your site. If you do not wish to have these pages running on a production server you should exclude them before you commit to production. To view pattern pages, go to "http://your-site/themes/your_theme/pattern-lab" or "http://localhost:3000/themes/pattern-lab/pattern-lab/public/" (when Browser Sync is running), or else "http://your-site/themes/custom/your_theme/pattern-lab" and "http://localhost:3000/themes/custom/pattern-lab/pattern-lab/public/" if you placed your theme inside a "custom" subdirectory of /themes.

  6. Gulp will watch for changes in your files. Not only will your Sass files automatically process into CSS, but any changes to your Pattern Lab patterns and Drupal theme template files will trigger appropriate changes as well. This includes reloading Browser Sync on each change so that the changes appear right away in your browser.

  7. Use control-c to stop Gulp watch tasks. When you use the command gulp build-dev to start development, watch tasks will continue to run and Browser Sync will refresh your browser with each change. When you wish to stop these processes, use the keyboard command control-c (assuming you are developing on a Mac). This will stop all tasks and the site will no longer be accessisble from http://localhost:3000.

  8. Put theme images in /img-src. When you add image files in the /img-src directory, Gulp will automatically recognize those files, processing them for optimization, and move a copy to the /images directory. You should use /images in the path of your images when referencing them in SCSS.

  9. Put theme template files in /templates. This directory already contains several template files, lifted directly from Classy theme. Use these or add new ones within this file structure.

  10. Extra time is needed before the browser refreshes when you change template files. When you make changes to Drupal template files or add new files, a Gulp task will clear Drupal cache and refresh the browser. Drupal requires that cached is cleared after template change, so a Drush command is added to the the watch sequence for template files. This step takes longer to run than other changes, so expect to wait at least 15 seconds before your changes are reflected in the browser. (See this issue for more details.)


A starter theme for Drupal 8 that contains several development tasks handled by Gulp.







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