https://docs.magento.com/m2/ce/user_guide/design/configuration.html

Design Configuration

The Design Configuration makes it easy to edit design-related rules and configuration settings by displaying the settings on a single page.

To edit the design configuration:

1.

On the Admin menu, tap Content. Then under Design, choose Configuration.

2.

Find the store view that you want to configure. Then in the Action column, click Edit.

The page displays the current design settings for the store view.

3.

To change the Default Theme, set Applied Theme to the theme that you want to apply to the view.

If no theme is specified, the system default theme is used. Some third-party extensions modify the system default theme.

4.

If the theme is to be used for only a specific device, do the following:

a.

Under Design Rule section under User Agent Rules, tap Add New User Agent Rule.

b.

In the Search String column, enter the browser ID for the specific device.

c.

A search string can be either a normal expression or Perl Compatible Regular Expression (PCRE). To learn more, see: User Agent. The following search string identifies Firefox:

• /^mozilla/i

d.

In the Theme Name column, choose the theme that is to be used for the specified device.

e.

Repeat the process to enter additional devices. Search strings are matched in the order they are entered.

5.

Under Other Settings, expand each section. Then, follow the instructions in the linked topics to edit the settings as needed.

• Pagination
• HTML Head
• Header
• Footer
• Search Engine Robots
• Product Image Watermarks
• Transactional Emails

6.

When complete, tap Save Configuration.