Styling the `+choices` select for landing page

The idea is to let visitors select who they are on the landing page:

> Enterprise
> Startup
> Engineer
> Software Agency

Same UI as for the docs, but we'll need something like the following to prominently let visitors know all the choices:
- https://github.com/brillout/docpress/issues/139

Beyond the `focus` idea, we'd need to add a `rotate` option so that the selection automatically rotates. Not sure yet what should happen if the user selects a choice (does it permanently prevents the rotation?).

I'm open to further ideas and suggestions.

FYI @phonzammi

Start from the landing-page `+choices` select and compare its UI with the docs select referenced in the issue. Before implementation, clarify the visual treatment, the `rotate` behavior, and what happens after a visitor makes a selection. Done means the choices are prominent and the agreed selection and rotation behavior works consistently.

Written by the indexing model from the issue text.