cover: in the frontmatter picks one of the ten below, ordered by how loudly the opening slide announces itself rather than alphabetically.

cover-image: names the picture, and four of the ten draw one: split, hero, beside and above. On the last two it is only the fallback – they take whatever you write under the ## title: heading, so a ::: draw can be the cover.

cover-ratio: is how much of the slide the picture takes, as a percentage between 15 and 75. Only the three that divide the slide read it – split, beside and above. A percentage and not a W:H ratio: the shape of the frame comes from the projector, and this splits it.

cover-align: puts the block of text at the top, the middle or the bottom. The seven compositions that leave the block any freedom read it.

Set either of the last two keys on a composition that has already settled the question and the build stops with an error rather than ignoring the line.

A sentence set alone on a slide with a name under it already reads as a quotation, so there is no mark: no hanging curly quote, no glyph behind the words, no rule beside them.

The claim is what you write under the ## title: heading. A quote cover without one fails the build.

## closing: draws the last slide in whatever composition cover: names, so the room sees the shape the lecture opened with.

What it carries is different: your own heading, sub-heading and text, and neither the presenter line nor the info block – the room learned who is talking and where an hour ago. The last slide of this lecture is one.

A divider has one job: to say that a new part starts here, and that it is part of the thing you are already in. One that can be mistaken for the title slide has failed at it.

The live part is set larger and in full ink; the parts before and after it recede. What carries progress is where the live item sits as it walks down the list, so the recession only has to say not this one. The live part is a size and not a third shade: two greys read from the back of a room, three do not.

section-mark: puts a short word over the heading. This lecture writes Part. Write nothing and nothing is drawn there.

Whatever you write between a # Heading and the first ## heading under it becomes the divider's slide. Ordinary markdown is the words, a ::: backdrop is the picture, a ::: draw is the figure.

Those three are what a divider takes; the other directives belong inside a ## slide. The words do print, as a short paragraph under the part title. The divider slide itself never prints.

When a divider's body is nothing but a figure, the figure goes beside the heading – stacked, a part title, an agenda and a drawing are three blocks down one axis with nothing across it.

Prose under a heading is an opening paragraph and stays stacked, which is how the quotation divider in Part 1 comes out.

::: cards 3 puts three boxes side by side, and an item is whole or it is nowhere. ::: cols 3 is the other thing: one flow of text the browser balances across three columns, so a paragraph can spill from the foot of one into the head of the next. Use cards for three things, columns for one long argument.

The ground word says what is behind the text, and a row wears one at a time: these two are set to accent and to the default panel, whatever their cards say. outline is on the slide before this one, and corner is a separate question.

size: auto counts the words in the longest card: three or fewer sets the row large, twelve or fewer medium, more than twelve small. One size for the whole row, never one per card.

Alignment then follows the size, a single word centring and a sentence ranging left. A row that carries a second level ranges left whatever its heads measure, so the heads do not jump when the reader presses C.

detail: fold is the default, so the levels under the first are in the printed hand-out and off the projection, and C switches between the two. This deck opens with everything showing, because its frontmatter says collapse: none; press C once here and the second level folds away.

A term in a small card on the left, its explanation beside it, several stacked. It takes the same words in braces as ::: cards, the same automatic size, the same fold and the same print rules. Only the arrangement of an item differs.

Every term gets the same column width, so the explanations line up down the slide however long the terms are.

::: backdrop dusk {cover} reveal full, right 52% gives the picture one place per beat – one press of Space – and the last place stays. Two moves come out of it: a picture that retreats to free the space the words need, and one that grows over the words and covers them.

What moves is the window, not the picture. The photograph is painted across the whole slide either way and the frame opens and closes over it, so nothing zooms or slides about while it is being revealed.

::: overlay {…} from 1 keeps the block off the slide until the first press of Space. One number, not a list: an overlay is either on the slide or it is not, where the backdrop's list says where the picture is at each beat.

An overlay fades in where a reveal segment simply appears. A segment is part of the flowing text, so what follows it closes up as it arrives; an overlay sits in its own cell over the picture and nothing else moves.

Four groups of words go in the braces after ::: backdrop, at most one from each, and the first of every group is what you get by saying nothing.

veil puts the theme's own page colour over the picture, not white, so ordinary text stays readable on a photograph in all seven themes. invert darkens the picture and turns the text light instead, which is what the divider at the start of Part 2 does.

Nine places, five backgrounds, four widths. Aim two overlays at the same corner and they stack rather than landing on top of each other.

{.bare} keeps a heading out of the projection and leaves it everywhere else. Writing no heading at all would cost the slide, the printed document and the search index together; a talk that is a run of figures with speaker notes usually wants to lose only the first.

So ## figure: How a crawl is scored {.full #id .bare} prints the heading, indexes it, and draws nothing on screen. style: {headings: off} says the same for a whole deck. Press / and search for measurement loop: it matches this slide and the next one, and the next one carries no heading on screen at all.