<div class="nav-wrap">
    <nav id="mainnav" class="mainnav" role="navigation">
        <?php
            wp_nav_menu( array( 'theme_location' => 'primary', 'fallback_cb' => 'themesflat_menu_fallback', 'container' => false ) );
        ?>
    </nav><!-- #site-navigation -->  
</div><!-- /.nav-wrap -->