By default, the body_class() function adds some class to the <body> tag to allow you to style your site more easily. But unfortunely, no extra class is added when your template has a sidebar. Here is a imple function to solve this problem.
To apply the hack, just paste the code below into your functions.php file.
function wpfme_has_sidebar($classes) { if (is_active_sidebar('sidebar')) { // add 'class-name' to the $classes array $classes[] = 'has_sidebar'; } // return the $classes array return $classes; } add_filter('body_class','wpfme_has_sidebar');
Thanks to WP Function for the tip!