A section
This is the content slot. A page built from this shell replaces this prose block with its own components, in the order the other templates show. The shell itself adds nothing beyond the canonical frame: the skip link, the government banner, one site-wide notice, the header, one main with the id the skip link targets, and the footer.
Nothing on this page is styled outside the system, and that is now enforced rather than promised: templates.css sets no page rhythm and reaches no system class, so every measurement here is the components' own behavior. A template that overrides the model cannot be read as an example of it.
This paragraph is set to the system's text measure, and the measure is counted in characters, not pixels. It binds 54ch, calibrated to about 72 characters in this face — the ch unit is the width of a zero, which runs wider than an average letter, so the count and the unit are two different numbers and only one of them is a design decision. Because ch resolves against each element's own font, the lede above holds the same line at a larger size, and so would this passage at any size. A max-width that measures a box — a form, a modal, a set container — stays in pixels: characters are a fact about type, and a box has none.