public function contentClass($classes = [])
    {
        $classes = !is_array($classes) ? explode(' ', $classes) : $classes;
        $classes[] = sprintf('main-%s', $this->template);
        $classes[] = 'main-content';

        if (is_active_sidebar(sprintf('sidebar-%s', $this->template))) {
            $classes[] = 'col-sm-8 col-md-9';
        } else {
            $classes[] = 'col-sm-12';
        }

        $classes = apply_filters('novusopress_view_content_classes', $classes);
        $output = sprintf('class="%s"', implode(' ', $classes));

        return apply_filters('novusopress_view_content_class_output', $output);
    }