Article layout v2 and summary

Working on the live blogs summary is also a good time to start thinking about the new design because the layout changes will impact both. 

- [new] Layout: first iteration towards adapting the article column layout as per the new designs
- [new] Layout: left and right outer spacing on mobile portrait is 10px (instead of 16px)
- [new] Layout: left and right outer spacing on mobile landscape and above is 20px (instead of 16px)
- [new] Summary is pulled from live events (behind a switch) and presented on top of the page to the user. This is the very first iteration of it, it does not deal at all with edge cases. For now it does not even pull the summary into the sidebar. /ping @phamann 
- [improved] Layout: Article layout is a lot more robust when multiple elements are in the right sidebar
- [improved] Better performance for social buttons. Forcing them to always be the same size (between right col and bottom of article)

Sorry it's all in one commit. I messed up the history with a `commit --amend` and I did not know how to rewrite the history.

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