A lemma box.

This page is a working example of the structure the rest of the site is written in. It uses the real proposition model and the real template; nothing here is mocked up in HTML.

A page's body is a list of sections, and each section renders as its own box. Sections of kind lemma come first, before the proposition, because that is the order Euclid's text puts them in.

Example page

The proof field is ordinary markdown with three additions.

The first is an element reference. Writing A or AB in the prose binds it to the figure alongside — hover the letters here and the matching part of the diagram lights up, and hovering the diagram works in reverse.

The second addition is a justification. A step that leans on something earlier names it, and it renders in the margin beside the step rather than interrupting it.

The same figure also carries a slide walk. The element list above is the only description of the geometry; the slides say which parts of it are on screen at each step, so the static diagram and the stepped proof cannot disagree. Press the present control under the figure to walk it.

The third addition is the citation token used in commentary rather than proof — @I.47 resolves to whichever URL that proposition currently has, so the prose survives a change of scheme.

A note box.

A section of kind note or remark carries its commentary inside its own box, because the box is the remark. These come after the proposition, matching the layout of the books that have them.

Below this you would normally see a referenced by table, listing the pages whose justifications point here. It is empty on this page: the reverse index is built by walking the text itself, so an example living outside it neither appears in that index nor inserts itself into anyone else's.