//======================================================================
// CUSTOM HEADER - MAIN PAGES
// Adds a section below the Main Header
//======================================================================
function mp_custom_header_below_menu( $content ) {
    $custom_header = '<header id="header-below-menu">';
        $custom_header .= do_shortcode('[et_pb_section global_module="27339"][/et_pb_section]');
    $custom_header .= '</header> <!-- #header-below-menu -->';
    return $content . $custom_header;
}
add_filter( 'et_html_main_header', 'mp_custom_header_below_menu' );