Attempting to parse HTML with regular expressions is an infamous pitfall, and a great example of using the wrong tool for the job. It's generally accepted to be a bad idea, for a multitude of reasons.

There's this famous Stack Overflow answer about why you should never, ever do it. In fact, this answer got so popular that it was used like a copypasta in some circles. Every time I stumbled upon it, I would think how there's a lot of truth in it - but at the same time, I couldn't agree in full...

But... can't you, really?