Customize the KnpMenuBundle

CSS works for this case, but sometimes you might need to add or change the markup more significantly. For that you can use a custom renderer as defined here: https://github.com/KnpLabs/KnpMenuBundle/blob/master/Resources/doc/custom_renderer.md

An example of a bundle that does this is the MopaBoostrapBundle I’ve highlighted the important parts here.

The service definition where the knp_menu.renderer tag is added:

services:
    mopa_bootstrap.navbar_renderer:
        class: Mopa\Bundle\BootstrapBundle\Navbar\Renderer\NavbarRenderer
        arguments: [ @service_container, [] ]
        tags:
            # The alias is what is used to retrieve the menu
            - { name: knp_menu.renderer, alias: navbar }

and the twig template can be written like so, for example.

<div class="navbar {{ (navbar.hasOption('fixedTop') and  navbar.getOption('fixedTop')) ? 'navbar-fixed-top' : '' }}">
    <div class="navbar-inner">
        <div class="container{{ (navbar.hasOption('isFluid') and navbar.getOption('isFluid')) ? '-fluid' : '' }}">
            <a class="btn btn-navbar" data-toggle="collapse" data-target=".nav-collapse">
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
            </a>
            {% if navbar.hasOption('title') %}<a class="brand" href="https://stackoverflow.com/questions/11226963/{{ path(navbar.getOption("titleRoute')) }}">{{ navbar.getOption('title') }}</a>{% endif %}
            <div class="nav-collapse">
                {{ navbar.hasMenu('leftmenu') ? knp_menu_render(navbar.getMenu('leftmenu'), {'currentClass': 'active', 'ancestorClass': 'active', 'allow_safe_labels': 'true'}) : '' }}
                {% if navbar.hasFormView('searchform') %}
                    {%- set form_view = navbar.getFormView('searchform') -%}
                    {%- set form_type = navbar.getFormType('searchform') -%}
                    {%- set form_attrs = form_view.vars.attr -%}
                    {% form_theme form_view _self %}
                    <form class="navbar-search pull-{{ form_attrs.pull|default('left') }}" method="{{ form_attrs.method|default('post') }}" action="{{ path(navbar.getFormRoute('searchform')) }}">
                    {{ form_widget(form_view) }}
                    </form>
                {% endif %}
                {{ navbar.hasMenu('rightmenu') ? knp_menu_render(navbar.getMenu('rightmenu'), {'currentClass': 'active', 'ancestorClass': 'active', 'allow_safe_labels': 'true'}) : '' }}
            </div>

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