When I click on notification link open the page with only html codes. How can I fix it?

Question

I use on-site-notifications plugin on my website. Everything worked good, but I can't understand why, now when I click on notification link, I see page without any style, looks like below:

This plugin is so important for me, so please help me to fix this

Comments

Probably the plugin URL is https but your site is not https ready. Mainly the css and js files should be loaded via https

---

Please check my website:
https://www.tibbforum.com/qa/index.php
It was working until now, I can't undersant what changed