The HTML and PHP code for the side bar can be found in the
sidebar.php file in your theme directory. The side bar loads WordPress Widgets. You can manage your widgets in the WordPress Dashboard. Navigate to Appearance | Widget and configure the widgets.
Each widget has a built-in HTML structure with CSS classes. You can change or modify the HTML and CSS structure when you register your side bar. The JBST 4 theme's side bars are registered in the
assets/functions/sidebar.php file of the theme as follows:
register_sidebar(array( 'id' => 'sidebar1', 'name' => __('Sidebar 1', 'jbst-4'), 'description' => __('The first (primary) sidebar.', 'jbst-4'), 'before_widget' => '<div id="%1$s" class="widget %2$s">', 'after_widget' => ...