Navigation drop-down problem
You can use entry.level in a conditional:

{% set entries = craft.entries.section('spb') %}
{% nav entry in entries %}

    {% set liTagAttributes = entry.level == 1 ? 'class="uk-parent" data-uk-dropdown' : 'class="uk-child"' %}

    &lt;li {{ liTagAttributes|raw }}&gt;
        &lt;a href="{{ entry.url }}"&gt;{{ entry.title }}&lt;/a&gt;
        {% ifchildren %}
            ...
        {% endifchildren %}
    &lt;/li&gt;

{% endnav %}


I set a intermediate var to keep the template code clean. If you don't have many levels in your structure, you could also consider to not use the nav tag at all and nest your navigation levels using hasDescendents and getDescendents(1) (see the example code I posted here).