Oh, so you're using Google Docs' viewer to view a PDF hosted elsewhere? Interesting, I didn't know that was possible. Why not just link to the PDF directly?
That would be a client side issue - your browser is using Google Docs to display the pdf. What’s in the repo is a pdf only, that works equally well in Foxit or whatever you like.
…Why is a book about LaTeX written in Google Docs?
why it is writtent in Google Docs -_- ? I have made an online preview, but it is just special repo which is hosted book in .pdf
Oh, so you're using Google Docs' viewer to view a PDF hosted elsewhere? Interesting, I didn't know that was possible. Why not just link to the PDF directly?
That would be a client side issue - your browser is using Google Docs to display the pdf. What’s in the repo is a pdf only, that works equally well in Foxit or whatever you like.
The link in the repo explicitly links to Google Docs: https://docs.google.com/viewer?url=https://raw.githubusercontent.com/AnMnv/AnMnv.github.io/master/eBook.pdf
If I open the PDF directly (which GitHub's interface makes unnecessarily difficult), it doesn't open in Google Docs.
https://github.com/AnMnv/eBook/blob/main/eBook.pdf here is just the link on .pdf book but the names in TOC in not "clickable" that is why I choose online preview in this way)
If you link to the raw file, it's going to open in the browser's PDF viewer, where links are clickable.
in this case, downloading starts immediately, it is not ok (at least in my case, I want to have online preview)
Looks like your browser doesn't have a PDF viewer built in. You should install an extension that adds it (PDF.js), it's really useful.
That would be a combination of your settings, and headers coming from GitHub.