Macro pref 

macro_rules! pref {
    ("layout.css.stylo-local-work-queue.in-main-thread") => { ... };
    ("layout.css.stylo-work-unit-size") => { ... };
    ("layout.css.stylo-local-work-queue.in-worker") => { ... };
    ("layout.css.system-ui.enabled") => { ... };
    ("layout.css.fit-content-function.enabled") => { ... };
    ("layout.css.outline-offset.snapping") => { ... };
    ("layout.css.relative-color-syntax.enabled") => { ... };
    ("layout.css.stretch-size-keyword.enabled") => { ... };
    ("layout.css.marker.restricted") => { ... };
    ("layout.css.webkit-fill-available.enabled") => { ... };
    ("layout.css.webkit-fill-available.all-size-properties.enabled") => { ... };
    ("layout.css.font-variations.enabled") => { ... };
    ($string:literal) => { ... };
}