Converting from a WordPress theme
Well, here is the code that I've put in place. So far it's respecting the CSS selector patterns that the WordPress theme rendered. 

&lt;div id="navigation" class="ten columns clearfix"&gt;
    &lt;div class="menu-navigation-menu-container"&gt;
       &lt;?php 
       print theme('links__system_main_menu', array(
         'links' =&gt; $main_menu, 
         'attributes' =&gt; array(
           'id' =&gt; 'nav', 
           'class' =&gt; array('menu')), 
         'heading' =&gt; t(''))
       ); 
       ?&gt;
    &lt;/div&gt;
&lt;/div&gt;