leek/add_slug_to_body_class.php

## add_slug_to_body_class.php
<?php

// Alternative:
// Install https://github.com/roots/soil

// Add slug to <body> class
add_filter('body_class', function ($classes) {
    // Add post/page slug if not present
    if (is_single() || is_page() && !is_front_page()) {
        if (!in_array($slug = basename(get_permalink()), $classes)) {
            $classes[] = "page-{$slug}";
        }
    }

    return $classes;
});
	<?php

	// Alternative:
	// Install https://github.com/roots/soil

	// Add slug to <body> class
	add_filter('body_class', function ($classes) {
	// Add post/page slug if not present
	if (is_single() \|\| is_page() && !is_front_page()) {
	if (!in_array($slug = basename(get_permalink()), $classes)) {
	$classes[] = "page-{$slug}";
	}
	}

	return $classes;
	});