Working with Themes
Themes are used to change the appearance of your Confluence site or spaces. You can download and install other themes from the Atlassian Marketplace.
Once you've installed a theme, you can apply it to the whole site or to individual spaces.
To see the themes installed in your site, go to Settings in the Confluence sidebar > Themes. You'll see a list of all the themes installed in your site.
When a new space is created, the theme applied to the whole site will be applied by default to the new space. To change colors for individual spaces, you'll need to download a theming add-on from the Atlassian Marketplace.