… and when I click Open Site in New Window button, it displays:
looks like there security issue on that page
looks like it pretend to be mdn while it’ not
are you sure of that page ?
where did you get link to that page?
It’s the embedded example at https://developer.mozilla.org/en-US/docs/Learn/HTML/Introduction_to_HTML/HTML_text_fundamentals#active_learning_marking_up_our_recipe_page. It displays correctly for me. When I open the URL in the second screenshot directy, it also works: https://developer.mozilla.org/en-US/docs/Learn/HTML/Introduction_to_HTML/HTML_text_fundamentals/_sample_.Playable_code_4.html
Maybe it was a temporary issue? @dika.alfred could you please test again?