Update all templates to have them follow the same margin and main header

[flummer]

The styling and markup for the top part of the different pages on the site seems to be more or less random, and only some use a proper H1 (some use H2, others H3 or a div or span).

It's the same with the short description directly below the header, that also jumps between pages with different sizes and weights.

In backoffice (and a few other places) there are also a single panel box around all the content, which eats up horizontal margin, especially on small screens like mobile phones.