Associate posts to region

[Trello card](https://trello.com/c/3tfOhrjd/16-as-a-user-i-can-browse-all-posts-within-a-geographic-region-and-category)
Percentage widths tend to be better as they scale with the page. You can set a max-width, min-width, and percentage if you want. Fine to ignore for now, just saying