grav-lecampus/user/themes/lecampus/templates/partials/layout.html.twig

{% set item_col = show_sidebar ? 'col-9 col-md-12' : 'col-12' %}
{% set sidebar_col = show_sidebar ? 'col-3 col-md-12' : 'col-12' %}

    <div id="item">
        {% block item %}{% endblock %}
        {% if show_sidebar %}
        <div id="sidebar" class="column {{ sidebar_col }}">
          {% block sidebar %}
          {% include 'partials/sidebar.html.twig' %}
          {% endblock %}
        </div>
        {% endif %}
    </div>