makeover-geometry

The invariant half of the make-family design system. makeover resolves colour, which varies by theme; this crate carries everything that does not.

Spacing is a relationship, not a size

The Mac OS 8 Human Interface Guidelines specify white space by what two things are being separated, and define no grid unit. A control and its satellite pop-up sit 4 pixels apart; peers stacked in a list get 6; a group box's inner margin is 10; separated groups and rows of push buttons get 12.

So the vocabulary here names the relationship and lets the size follow, the same way surface-raised names an intent and lets the hex follow:

Whether a gap should be 6px or 8px is unanswerable on its own. Whether two things are peers is not. That is the whole argument for the layer.

A raw step-* scale sits underneath for distances no relationship describes, such as an optical nudge inside a badge. Reaching for it is a smell worth a second look.

Ratios, not pixel counts

The deliberate departure from the HIG, which is written in hard device pixels because in 1997 there was one pixel density and one text size.

Every step is a ratio of one base unit, --geometry-base, which defaults to 1rem. At that base the ratios land exactly on the HIG's numbers, so nothing is lost in translation. What is gained: the layout tracks the user's text size instead of fighting it, an accessibility setting is one value rather than a sweep, and the scale means the same thing at any display density.

--step-snug: calc(var(--geometry-base) * 3 / 8);   /* 6px at the default base */
--gap-peer:  var(--step-snug);

Density presets

Because no call site names a size, a preset can change what every relationship resolves to without touching one of them. Mobile and desktop builds should differ mostly by which preset they emit.

The presets are not scaled copies of each other, which is also why a single base scalar could not express this. Touch wants more room between things you tap and less around the edges, since a fingertip is coarse and outer margin is screen you do not get to use. gap-peer and gap-section open up; gap-pane and gap-page tighten. gap-bound never moves — it is the one relationship that says "these are one object".

use makeover_geometry::{Density, geometry_css_vars, gap_css_overrides};

let mut css = geometry_css_vars(Density::Pointer);
css.push_str(&gap_css_overrides(".ui-mode-mobile", Density::Touch));

The override block emits only the relational layer. The base and the scale are declared once.

Surfaces, and why a terminal is not a third preset

A terminal is not a density. It is a surface whose smallest representable step is one cell rather than one pixel, and that single difference is the whole of it. Ratio::quanta takes a quantum and answers in whole units of it, so the relational vocabulary reaches a character grid with nothing added.

Quantising is not a terminal special case either. A display quantises to the pixel; it is only that rounding 6.0 to the nearest pixel is uninteresting, while rounding three eighths of a cell to the nearest cell decides the layout.

use makeover_geometry::{Density, Gap, Surface};

let t = Surface::terminal();
assert_eq!(t.gap(Gap::Peer, Density::Pointer), 0);     // cells
assert_eq!(t.gap(Gap::Section, Density::Pointer), 1);
assert_eq!(t.gap(Gap::Page, Density::Pointer), 2);

bound and peer collapsing to zero cells is correct rather than lossy: in a grid that dense, both relationships are expressed by adjacency. A coarse surface genuinely has fewer distinctions available, and the model should say so instead of inventing a gap to keep six names apart. What it must never do is invert two relationships, and there is a test across several quanta pinning that.

So three orthogonal axes: Gap is what is being separated, Density is who is operating it, Surface is what it is drawn on.

Consumers

Web surfaces bake the CSS in at build time; unlike colour, none of this changes at runtime, so there is nothing for JS to apply on load. egui and ratatui surfaces resolve through Surface instead, which is the reason this is a crate rather than a stylesheet.

Licence

MIT.