How to add a class to the main page when inserting a header via posthtml-include?

Question

Node.js

Good evening. Essence of the question: there is a site layout in which I want to put the header and footer into separate blocks and connect them through the tag , but on the main page the header has an additional class. How to insert a header on a page, but add an additional class for index.html?
<include src="***"></include>

Answer 1

Look in the direction of posthtml-mixins
Or use templating, I started using pug
in due time Example and my tool for layout gulp-front

<mixin name="header" class>
  <header class="header {{ class }}">Header</header>
</mixin>