Function gap_css_overrides 

pub fn gap_css_overrides(selector: &str, density: Density) -> String

Emit a density preset as a scoped override block.

Only the relational layer and the target floor are emitted: the scale and the base do not change between presets, so an app ships geometry_css_vars at its default density and one of these per mode class it supports. Of the gaps, only Gap::Peer, Gap::Group and Gap::Section move with the input device; Gap::Bound and the two shells keep the value the base declared, so a touch preset never overrides a compact-window shell.

let css = gap_css_overrides(".ui-mode-mobile", Density::Touch);
assert!(css.starts_with(".ui-mode-mobile {\n"));