Menu item in view when loading page

[mb]

Currently, the scroll position is reset to the top on each page load. Having the current position in view when opening a page would make navigation easier. Keeping the current scroll position between page loads would be even better.

Similar how mdbook does it: https://doc.rust-lang.org/stable/book/ch13-01-closures.html

[Keats]

I'll take a PR for it