Plate WordPress body class function: adds more classes to your WordPress posts + pages to help with CSS

plate-body-class.php

<?php
// Body Class functions
// Adds more slugs to body class so we can style individual pages + posts.
// In your SCSS/CSS, use .page-yourslug {} to add styles for that page or post.
add_filter( 'body_class', 'plate_body_class' );

function plate_body_class( $classes ) {

    global $post;

    if ( isset( $post ) ) {

        /* $classes[] = $post->post_type . '-' . $post->post_name; *//*Un comment this if you want the post_type-post_name body class */
        $pagetemplate = get_post_meta( $post->ID, '_wp_page_template', true);
        $classes[] = sanitize_html_class( str_replace( '.', '-', $pagetemplate ), '' );
        $classes[] = $post->post_name;

    }

    if (is_page()) {

        global $post;

        if ( $post->post_parent ) {

            # Parent post name/slug
            $parent = get_post( $post->post_parent );
            $classes[] = $parent->post_name;

            # Parent template name
            $parent_template = get_post_meta( $parent->ID, '_wp_page_template', true );
            
            if ( !empty($parent_template) )
                $classes[] = 'template-'.sanitize_html_class( str_replace( '.', '-', $parent_template ), '' );

        }
        
        // If we *do* have an ancestors list, process it
        // http://codex.wordpress.org/Function_Reference/get_post_ancestors
        if ($parents = get_post_ancestors( $post->ID )) {

            foreach ( (array)$parents as $parent ) {

                // As the array contains IDs only, we need to get each page
                if ( $page = get_page($parent) ) {
                    // Add the current ancestor to the body class array
                    $classes[] = "{$page->post_type}-{$page->post_name}";
                }

            }

        }
 
        // Add the current page to our body class array
        $classes[] = "{$post->post_type}-{$post->post_name}";

    }

    return $classes;

}