How to install a new theme?

Publii stores themes in two places:

in the Publii/themes directory, where all themes currently installed in the Publii app are stored and these themes are available to use in all websites available in your Publii installation,
inside each website's input folder, which includes a theme directory which only stores the theme files used on that specific website.

In this case you can have older version of the theme in your site, than the version currently installed in Publii. It protects your websites before unintended update of the themes.

To install a new theme in your Publii website, you have to make two operations:

Install the new theme in Publii, to make it available for all websites
Select and install previously installed theme on the selected website.

Installing a new theme in Publii

Download the theme as a ZIP file, for example from the Publii Marketplace. You don't need to extract it. In Publii, open the three-dot menu in the top-right corner of the app window and click Themes. Click Install theme and select the ZIP file, or drag the file onto the Themes screen. Publii installs the theme and adds it to your theme library.

Installing a theme on your website

Go to Site Settings and open the Theme drop-down list under Basic settings. Themes from your library are listed in the In your theme library (copied to this site on save) section. Select the theme and click Save settings. If the site already uses another theme, confirm the switch with Change theme.

When you save, Publii copies the theme files from the application themes directory to your website. If a theme with the same name already exists on your website, the new copy overwrites it, and you lose any changes made directly in the theme files. Keep such changes in theme overrides, which stay intact when you update the theme.

Before you switch the theme of an existing website, create a backup. The Installing, Using and Updating Publii Themes guide covers the whole process, including theme updates and removing unused theme copies.

You can also copy the theme directory manually to the website's input/themes directory.