http://lists.w3.org/Archives/Public/www-style/2013May/0361.html

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> Similarly, I've seen a lot of the social sites that support j/k style
> navigation between posts do this: plus.google.com and the tumblr feed I'm
> pretty sure do it.

This doesn't update the URL bar or the history, and wants to scroll an  
element into view, so scrollIntoView() seems like the best fit here.

An issue though is that plus.google.com's j/k navigation wants to position  
the post under the header, so a normal link doesn't work, and the current  
scrollIntoView() doesn't work, either (the post would be positioned behind  
the header).

We could make scrollIntoView() take an argument that supports positioning,  
which has been proposed in  
https://www.w3.org/Bugs/Public/show_bug.cgi?id=17152 but that proposal  
seems suboptimal here where we want "under the header" rather than "X%  
 from the top of the viewport".

For pages that have a fixed header, I think it would be nice to be able to  
offset navigations/scrolls to elements. For instance, we could introduce  
something like

@viewport { scroll-top-offset: 100px; scroll-left-offset: 50px; }

which would cause both <a href="#foo"> links and scrollIntoView() to  
scroll to that offset instead of the top of the viewport.

What do people think?
]]