<?php CSS_Modules\start('foo', 'component/main-article'); ?>
<article class="{foo.section}">
    <h1 class="{foo.heading}">My style is scoped.</h1>
</article>
<?php $foo.ob_get_clean(); ?>

<?php $cn = CSS_Modules\get_class_name; ?>
<article class="<?php echo $cn('foo', 'section'); ?>">
    <h1 class="<?php echo $cn('foo', 'heading'); ?>">My style is scoped.</h1>
</article>