if( !function_exists( 'mars_child_after_setup_theme' ) ){
    function mars_child_after_setup_theme() {
        //------------------------------ Add Image Size -----------------------------------------//
        remove_image_size( 'video-featured' );
        remove_image_size( 'video-lastest' );
        remove_image_size(  'video-category-featured' );
        remove_image_size('video-item-category-featured');
        ### sidebar
        remove_image_size( 'most-video-2col' );
        ### Blog
        remove_image_size('blog-large-thumb' );

        add_image_size('video-featured', 640, 360, true);
        add_image_size('video-lastest', 640, 360, true);
        add_image_size('video-category-featured', 640, 360, true);
        add_image_size('video-item-category-featured', 640, 360, true);
        ### sidebar
        add_image_size('most-video-2col', 640, 360, true);
        add_image_size('blog-large-thumb', 750, 422 , true);
    }
    add_action('after_setup_theme', 'mars_child_after_setup_theme', 99999 );
}