src/_header.html
<nav>
<ul>
<li class="@@activeclassHome">Home</li>
<li class="@@activeclassAbout">About</li>
</ul>
</nav>
src/index.html
@@include('_header.html', {activeclassHome": "active", "activeclassAbout": ""})
src/about.html
@@include('_header.html', {activeclassHome": "", "activeclassAbout": "active"})