It's clear that they use display table and table cell but not sure how to implement it, been playing with css for a while, couldn't nail it. Didn't found a plugin that does the job but css should do. Do I have to create a custom menu layout? I think not.
I'm using a wordpress menu with this plugin, and the header.php
<?php wp_nav_menu( array( 'theme_location' => 'primary', 'menu_id' => 'menu-header', 'fallback_cb' => false, 'container' => false ) ); ?> <a href="<?php echo esc_url( CP_ADD_NEW_URL ); ?>" class="obtn btn_orange"><?php _e( 'Post an Ad', APP_TD ); ?></a> <div class="clr"></div>