max / makenotwork

Derive the page's layout class from a described measure 69 of 72 templates carried `padded-page`, `centered-page` or `article-page` as a literal in `{% block body_attrs %}`, which made how wide a page runs a fact about the template rather than about the screen. 53, 13 and 3 of them, and the count comes out the same after the conversion because nothing about which page is which has changed. `shell::measure` maps `makeover_layout::Measure` to the three strings. The strings are unchanged and no rule in `style.css` is touched: what moved is where the choice is written down, from a class name in markup to a property the description layer names and every renderer has to answer. The old class names stay on the left-hand side of the rules because that is what the stylesheet matches, and renaming them is a separate change with no description in it. A test walks the templates and fails on a layout class still written by hand, so a new template pasted from an old one does not quietly reintroduce the literal. The four standalone tokens are screen identity rather than measure and are deliberately left alone.