site/_src/_includes/menu-main.html

<nav class="menu menu--main">
    <div class="row">

        <div class="grid grid--full grid-small--fit grid--center">
            <div class="grid__col">
                <a class="menu__logo" href="/">
                    <svg class="logo logo--sm" aria-labelledby="title">
                        <title>Logo</title>
                        <use xlink:href="/assets/img/sprite.svg#logo"></use>
                    </svg>
                </a>
            </div>

            <div class="grid__col">

                {% for link in site.data.menus.main %}

                    {% assign active = nil %}
                    {% if page.url contains link.url %}
                        {% assign active = 'active' %}
                    {% endif %}

                    <a class="menu__link" class="{{ active }}" href="{{ link.url }}">{{ link.title }}</a>

                {% endfor %}

            </div>
        </div>
    </div>
</nav>