Labels

Every part of a rendered slide carries a Typst label, and those labels are the whole styling surface. A deck reaches them with ordinary show rules, and a theme’s apply reaches the same ones. This page is the complete inventory.

Two kinds of rules cover a labeled region, split by what they touch. Properties of the content inside it pass through as ordinary set rules. Properties of its own block, its fill, stroke, and corner radius, go through m.surface, which wraps the labeled block in one that carries the paint. The styling page explains that split in full.

Cells

Each cell of a slide is a single block labeled with its own id.

mosaic-cell-IDAny cell, by the id its layout or grid gave it. This is the general form; the entries below are the ids the built-in layouts produce.
mosaic-cell-headerThe header of a content slide.
mosaic-cell-bodyThe body of a content slide, and the default cell for slide content with no layout.
mosaic-cell-footerThe footer of a content slide, and the usual home for a progress indicator.
mosaic-cell-titleThe title stack of a title slide.
mosaic-cell-authorsThe author block of a title slide.
mosaic-cell-detailsThe date and other fine print of a title slide.
mosaic-cell-sectionThe heading of a section slide.
mosaic-cell-imageThe image cell of an image layout.

A theme is expected to style at least mosaic-cell-title, mosaic-cell-section, and the content cells it uses. A theme that omits one renders that region in the engine’s bare defaults, and nothing warns about it.

Composed tiers

The title and section layouts are compositions rather than bare grids. Each text tier they emit carries its own label, so a rule reaches it without knowing how the variant is assembled.

mosaic-title-displayThe display line of a title slide, inside mosaic-cell-title. This is where a theme states the title’s display size and tracking.
mosaic-section-numberThe section numeral of a section slide.
mosaic-section-titleThe section’s title text.
mosaic-section-subtitleThe section’s subtitle, where the variant emits one.

Typography goes through these labels. Geometry does not: the spacers, rules, and offsets a variant composes itself from are produced during layout and no show rule reaches inside them. A size, weight, or color is always a label rule; an arrangement is the variant’s design.

Whole slide and planes

mosaic-slideThe entire cell grid of one slide. One rule here reaches every cell at once, which is what light text over a photograph wants. A mosaic-cell-* rule still refines it.
mosaic-backgroundThe full-slide plane behind the grid.
mosaic-foregroundThe full-slide plane in front of the grid.

Engine-owned labels

These carry rules from Mosaic itself rather than from a theme. A theme or deck rule on the same label overrides them, but the defaults are deliberate.

mosaic-note-headingThe heading on a printed speaker or notes page. Set black on white, because those pages are paper whatever the deck’s theme does.
mosaic-note-bodyThe note text on those same pages.
mosaic-overflow-warningThe diagnostic emitted when content exceeds its cell. Not a styling target.