We were jumping from h1 to h3 and some of these sections (cards and
processes) had h3 tags inside them.
My best guess is we were using h3 so the titles were smaller. So I'm
adding a CSS mixin to easily use a font size of a different heading tag.
We were having some style issues when adding the processes feed to the
goal view because of this lack of separation.
We're using a <section> tag so it's clear where the <header> tag belongs
to.
They were all following the same format.
Note we need to group the `see_all` translation keys together (the same
way it's done with the `most_active` keys) so we don't have an unused
translation warning.
We're also moving the "see all" link in processes outside the feed
content; the same way it's done in debates and proposals and removing
unnecessary classes in the processes feed: the column class is causing
the processes not to be aligned with the debates above them, and the
margin bottom is not needed because the margin of the footer is already
enough.