NoNumber is using preg_match and preg_replace to search the whole doc for it,
that is an overkill for such a simple change and an overload for your website.
the fastest would be to do this via custom.css or in template custom codes
Screenshot by Lightshot
what I posted previously is the correct way to do overrides with Yjsg v2
what you are doing with nonumber would be same as if I told you not to use Joomla MVC for overrides but to use some 3rd party extension.
An overkill and a php script to do the task of html or css.