{% assign top-level-layouts = 'theme,main' | split: ',' %}<!doctype html>
<!--[if lt IE 9]><html class="no-js lt-ie9" lang="en"> <![endif]-->
<!--[if IE 9 ]><html class="ie9 no-js"> <![endif]-->
<!--[if (gt IE 9)|!(IE)]><!--> <html class="no-js"> <!--<![endif]-->
  <head>

    {% include 'html-head-common' %}

    <!-- Header hook for plugins ================================================== -->
    {{ content_for_header }}

    {% include 'html-head-scripts' %}

  </head>

  {% comment %}
  Add the page template as a class for easy page or template specific styling.
  {% endcomment %}
  <body {% include 'html-body-attributes' %}>

    {% include 'html-body-top-scripts' %}

    {% include 'mobile-side-nav' %}

    <div data-headroom data-offset="160" id="header-container" class="header-container">

      {% include 'header' %}

    </div>

    <div id="body-container" class="body-container">

      <main class="main-content" role="main">

        {{ content_for_layout }}

      </main>

      {% include 'footer' %}

    </div>

    {% include 'html-footer-scripts' %}

  </body>
</html>


Test commit of the new branch
{% assign top-level-layouts = 'theme,main' | split: ',' %}<!doctype html>
<!--[if lt IE 9]><html class="no-js lt-ie9" lang="en"> <![endif]-->
<!--[if IE 9 ]><html class="ie9 no-js"> <![endif]-->
<!--[if (gt IE 9)|!(IE)]><!--> <html class="no-js"> <!--<![endif]-->
  <head>

    {% include 'html-head-common' %}

    <!-- Header hook for plugins ================================================== -->
    {{ content_for_header }}

    {% include 'html-head-scripts' %}

    <!-- new comment -->

  </head>

  {% comment %}
  Add the page template as a class for easy page or template specific styling.
  {% endcomment %}
  <body {% include 'html-body-attributes' %}>

    {% include 'html-body-top-scripts' %}

    {% include 'mobile-side-nav' %}

    <div data-headroom data-offset="160" id="header-container" class="header-container">

      {% include 'header' %}

    </div>

    <div id="body-container" class="body-container">

      <main class="main-content" role="main">

        {{ content_for_layout }}

      </main>

      {% include 'footer' %}

    </div>

    {% include 'html-footer-scripts' %}

  </body>
</html>