The body_class wordpress filter is nice for adding a lots of classes to the body tag that have information about what kind of page is currently being displayed. Probably for styling purposes. But for whatever reason, it doesn’t include a class for the current category (or categories) for a single post.
This following code adds all categories as classes in <body> tag
add_filter('body_class','add_category_to_single'); function add_category_to_single($classes, $class) { if (is_single() ) { global $post; foreach((get_the_category($post->ID)) as $category) { // add category slug to the $classes array $classes[] = $category->category_nicename; } } // return the $classes array return $classes; }
Filter Used
Filter Name: body_class

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