Grid should treat smaller columns different from larger.

[abea]

A while back I worked up something to this effect for WRT. Basically, grid columns below a third of the total number (12, usually) would get smaller sooner, while bigger columns would stay 100% width longer.

https://github.com/punkave/wrt/compare/hotfix/new-grid

I suggest we incorporate something like that here to avoid stuff like absurdly wide person teaser cards.