Bjc integration -- and lots of CSS work and cool stuff.

I'm bad at making small commits and being patient, so this PR should really be like 4 separate ones, but I'm fixing stuff. :)

However, some stuff is currently buggy so best not pull this yet!

Left to do:
- [x] Fix the file bug with a bad URL parameter
- [x] reduce top padding on mobile views
- [x] fix get feedback button size
- [x] remove the redundant grey border
- [x] increase usable width of content on topic pages