<?php

/**
 * Implements hook_preprocess_html().
 */
function schunder_preprocess_html(&$variables) {
  // Get the current path
  $current_path = \Drupal::service('path.current')->getPath();
  $internal_path = \Drupal::service('path_alias.manager')->getAliasByPath($current_path);

  // Assign it to body class
  $variables['attributes']['class'][] = str_replace("/", "", $internal_path);
}