Ask HN: How to defend against ด้้้้้็็็็็้้้้้็็็็็้้้้้้้้็็...

I've seen multiple pages or applications where using characters like ด้้้้้็็็็็้้้้้็็็็็้้้้้้้้็็็็็้้้้้็็็็็้้้้้้้้็็็็็้้้้้็็็็็้้้้้้้้็็็็็้้้้้็็็็ completely breaks layouts. As a developer, how should I defend my web applications against such characters, assuming I otherwise want to allow unicode characters in user input?