Include common website content across multiple pages
Some website content may be common across many pages on the site (e.g. a header or footer). Define this content on a single Confluence page and add it to many pages using the Confluence Include Page macro.
Type / (backslash) while editing a page, type Include Page and then select the macro from the list. The macro will be added to the page.
Select the macro and press the Edit icon (pencil).
Select the page of common content using the Page to Include field the in the configuration panel on the right hand side.
Content added this way will be included in the Entire page content variable when publishing a page to the cloud and can also be added to a Named content section. See: Use variables in an html template
Publish to Cloud for Confluence docs