Redux::setSection( $opt_name, array(
    'title'      => __( 'Mobile menu', 'redux-framework-demo' ),
    'id'         => 'header-mobile-menu',
    'subsection' => true,
    'fields'     => array(
            'id'       => 'header-mobile-menu-background',
            'type'     => 'color_rgba',
            'title'    => __('Mobile menu background Color', 'redux-framework-demo'),
            'subtitle' => __('Background color for mobile menu overlay', 'redux-framework-demo'),
            'default'  => array(
                'color'     => '#E2E2E2',
                'alpha'     => 1
            ),
            'transparent' => false,
            'output'   => array(
                'background-color' => '.mobile-menu',
            ),
        ),

) );