Adding class on a custom prebuilt layout

Hello,

I wan’t to create some prebuilt layouts for a website, it works well but I don’t know how to add a class to the row I created, here is my code :

      $layouts['cta-green'] = array(
          'name' => __('Call To Action - Green'),
          'description' => __('Green - Call to action' ),
          'screenshot' => get_template_directory_uri(). '/assets/images/layout-cta-green.png',
          'widgets' 		=> array(
                          0 => array(
                            'headline'  => array(
                              'text' 			=> "Image",
                              'tag'  			=> 'p',
                              'font_size'  	=> '28',
                              'color'  		=> '#ffffff',
                            ),
                            'divider' 	=> array(
                              'style'  		=> 'none',
                            ),
                            'info' 			=> array(
                                        'class' => 'SiteOrigin_Widget_Image_Widget',
                                        'id' 	=> '1',
                                        'grid' 	=> '0',
                                        'cell' 	=> '0',
                                      ),
                          ),
                          1 => array(
                          'title' 		=> "Text zone",
                          'text' 			=> '<h2>Call to action title</h2>
                          Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
                          <a href="#" class="btn">Lorem ipsum</a>',
                          'filter' 		=> false,
                          'info' 			=> array(
                                          'class' => 'SiteOrigin_Widget_Editor_Widget',
                                          'id' 	=> '2',
                                          'grid' 	=> '0',
                                          'cell' 	=> '1',
                                        ),
                          ),
                        ),
                        'grids' 		=> array(
                              0 => array(
                              'cells' => '2',
                              <strong>'class' => 'push-green',</strong> //doesn't work !!!
                              'style' => array(
                                  'background'=>'#1BB58C',
                                ),
                              ),
                        ),
                        'grid_cells' 	=> array(
                                      0 => array(
                                      'weight' 	=> '0.5',
                                      'grid' 		=> '0',
                                      'style' => array(
                                            'vertical_alignment' => 'center',
                                            'padding' => '0'
                                          ),
                                      ),
                                      1 => array(
                                        'weight' 	=> '0.5',
                                        'grid' 		=> '0',
                                        'style' => array(
                                            'vertical_alignment' => 'center',
                                            'padding' => '30px'
                                          ),
                                        ),
                                      ),
                        );

How can I do that ?

Thanks a lot