In my previous article, we learned to create a custom sub-theme using Bootstrap. And, in this article, we will learn to create sub-theme using Zurb foundation as a base theme in Drupal 8. We will also touch upon what is Zurb foundation framework, how to install it, and its feature components.

Why use Zurb Foundation as a framework?

Zurb Foundation is the first mobile-first responsive front-end framework. Some advance grid structure and feature elements make this framework different from other frameworks. Here are some of them:

• Advance Grid
  • X-Y Grid (New)
  • Flex Grid
  • Float Grid
     
• Feature Components
  • Off Canvas Container
  • Responsive Accordion Tabs
     
• Navigations
  • Dropdown Menu
  • Drilldown Menu
  • Accordion Menu
  • Responsive Navigation
  • Magellan

Additionally, this framework is  very easy to customize.

Building sub-theme with Zurb Foundation

• Download the Zurb Foundation theme from Drupal.org. Move it to your theme folder. 
   
• Install with the Composer. Composer install will manage all drupal site dependencies

  $ composer require 'drupal/zurb_foundation:^6.0'

• Zurb foundation can be easily extended by its sub-themes. Therefore, we will not modify any files in Zurb foundation or in its folder instead, we will create a sub-theme of zurb_foundation which is located in a folder outside of the root zurb_foundation/ folder.
  
  The examples below assume zurb_foundation and your sub-theme will be installed in themes/
• The purpose of creating a sub-theme is to make it easier to upgrade the base theme (Zurb foundation). The sub-theme should be placed in a separate folder under a custom theme folder.
   
• Standard folder structure will be:

  theme/
    -- contrib/
      -- zurb foundation/
  -- custom/
      -- my_theme/

Manual sub-theme setting

Zurb foundation provides Starter Kit with a base theme.

• Copy the Starter Folder out of the Zurb foundation and place it under custom theme folder and rename it with your theme name.
   
• Your theme name must start with an alphabetic character and can only contain a lowercase letter, number and underscore.

Setting up the basic information of sub-theme

Here, you have to rename the STARTER.info.yml.txt file with your theme name.

• Let say, your theme name is “my_theme”. Here, remove the .txt extension and then rename the file with my_theme.info.yml.
   
• Edit your my_theme.info.yml file and change "name: Foundation Sub-theme Starter" to "name: My Theme" and "description".
   
• Info file describes the basic things about your theme: its name, description, features, template regions, and libraries. Check out the Drupal 8 Theme Guide for more information on the same. 
   
• Edit your sub-theme with proper function names and then rename the STARTER.theme with my_theme.theme.
   
• Edit the my_theme.theme and theme-settings.php and replace ALL occurrences of "STARTER" with the name of your sub-theme.

Setting up your website’s default theme

• Log in as an administrator on your Drupal site, go to the Appearance page at admin/appearance and click the "Enable and set default" link next to your new sub-theme.
• 
• Bower and npm 
  This theme uses bower and npm. You will need both on your machine for developing your theme.
   
• Once you have installed both on your machine, run these command at the root of your sub-theme:
  • `npm install`
  • `bower install`
     
• Now, run gulp to compile the sass or gulp watch which will re-run every time we save the sass file. To stop watching files, press Ctrl+C.     

What else you need to do?

• Modify markup in Foundation core themes template files
• Add custom CSS and JS file to your sub theme