Redesign to align with the new nixos.org design

[garbas]

With #261 we didn't do as good as job as we could in terms of presenting results:

• The properties (Source, Homepage, Licenses, ...) need to be presented in a more clear form. Although there is always a problem with showing too little vs showing to much.

• How to the properties are shown (hovering over) is confusing. We must do a much better job.

https://github.com/NixOS/nixos-common-styles should be used as an input and help bring the design up to speed with nixos.org.