When I first used Google Translate, I’m almost certain that it worked as expected for in-page translation of https://www.s3blog.org/s3gt.html – certainly, it’s the page that I tested before writing this:
Now I see, there’s an integral feature – Translate this page – however it’s not working for me. A click on the button is recognised – the button darkens – but then nothing happens, no translation:
Similarly, the Google Translate extension does not have (or no longer has) the required effect.