{% block yandex_maps_widget %}
    <div id="{{ form.vars.id }}" style="width: {{ form.vars.width }}px; height: {{ form.vars.height }}px;"></div>

    {% for child in form %}
        {% if child.vars.value is empty %}
            {{ form_row(child, {
                value: form.vars.default[child.vars.name]
            }) }}
        {% else %}
            {{ form_row(child) }}
        {% endif %}
    {% endfor %}

    <script>
        new YandexMapsWidgetClass('{{ form.vars.id }}');
    </script>
{% endblock %}
{% block yandex_maps_widget %}
    <div id="{{ form.vars.id }}" class="{{ attr.class }}" style="width: {{ form.vars.width }}px; height: {{ form.vars.height }}px;"></div>

    {% for child in form %}
        {% if child.vars.value is empty %}
            {{ form_row(child, {
                value: form.vars.default[child.vars.name]
            }) }}
        {% else %}
            {{ form_row(child) }}
        {% endif %}
    {% endfor %}

    <script>
        new YandexMapsWidgetClass('{{ form.vars.id }}');
    </script>
{% endblock %}

Add an ability to set a class
Add an ability to set a class

Add an ability to set a class for a map's container