The Drupal 8 CSS framework is based on the popular Bootstrap 3 framework. Here are the steps to use the Drupal 8 CSS framework:
1. Download and install Drupal 8 on your local machine or web host.
2. Once Drupal 8 is installed, go to the website root directory (/var/www/html if Linux) and navigate to the /themes directory.
3. Create a new folder for your custom theme. For example, if your theme is called “mytheme”, create a folder called “mytheme” inside the /themes directory.
4. Inside the “mytheme” folder, create a file called “mytheme.info.yml”. This file contains the basic information about your theme, such as name, description, and dependencies. Here is an example of the contents of the file:
```
name: My Theme
description: A custom theme based on Bootstrap 3.
type: theme
core: 8.x
base theme: bootstrap
```
1. Save the “mytheme.info.yml” file and create a subfolder called “css” inside the “mytheme” folder.
2. Download the latest version of Bootstrap 3 from the official website and extract the contents of the archive to the “mytheme/css” folder.
3. Rename the “bootstrap.min.css” file to “mytheme.css”.
4. Open the “mytheme.css” file and make any customizations to the CSS to match your design.
5. Go to the Drupal 8 administration dashboard and navigate to Appearance > Themes.
6. Find your “mytheme” in the list of available themes and click “Enable and set default”.
7. View your website to see the changes made by the new theme.
Note: It is recommended to use a CSS preprocessor, such as SASS, to make it easier to manage and customize the CSS code. You can also use a CSS framework other than Bootstrap by modifying the base theme in the “mytheme.info.yml” file.
