apply CSS to all posts with a category LiveMap

Hello,

I want to keep a modal box with exit-intent from showing on posts with category LiveMap

I got the php code from
https://generatepress.com/forums/topic/change-header-background-for-category-or-pages/#post-120674

 add_filter('body_class','add_category_to_single');
    function add_category_to_single($classes) {
	if (is_single() ) {
		global $post;
		foreach((get_the_category($post->ID)) as $category) {
			echo $category->cat_name . ' ';
			// add category slug to the $classes array
			$classes[] = 'category-'.$category->slug;
		}
	}
	// return the $classes array
	return $classes;
}

And

.category-LiveMap .pp-modal-content {
    diplay:none;
}

But not working, am I doing this correctly?

Thanks