<?php
$categories = get_the_category($post_id);
if($categories){
echo '<ul class="category__list flex">';
foreach($categories as $category) {
echo '<li class="list__item"><a class="list__link" href="'. get_category_link($category->term_id) . '">' . $category->cat_name . '</a></li>';
}
echo '</ul>';
}
?>
$class = 'active';
foreach($categories as $category) {
echo '<li class="list__item '.$class.'"></li>';
if($class == 'active'){
$class = ''
}
}foreach($categories as $key => $category) {
echo '<li class="list__item'.($key == 0)?" active":"".'"></li>';
}