woah. Is that a universal thing or is it browser-specific? I've never seen that before.

edit: ah. Yeah it doesn't work on my phone (Pixel ... 1). It downloads the entire PDF and then just dumps me on the first page.

It's worked on every desktop browser I've tried it on. I haven't tried it on mobile. (Smartphones are not good for reading PDFs...)

The links are probably part of the PDF specification, but I guess will require support in every PDF reader in which you want to to use them.