A Sass compiler written in Rust, built to WebAssembly. Everything below compiles in this tab: no server, no Node, no network after the page loads. Change a theme value and a whole design system rebuilds.
You edited the source by hand, so these controls no longer drive it. Reset to use them again.
USWDS is 605 stylesheets and about 800 KiB of Sass. The page holds
the whole tree in memory and resolves every @use
against it, because the compiler's filesystem is an interface the
caller supplies rather than std::fs.
The theme controls rewrite the @use … with (…) block
and recompile from source, so you get the stylesheet the framework
would have produced. This is not a layer of CSS pasted on top.
The compiler asks for a file and gets bytes back, with nothing to await. An import therefore cannot be fetched while compiling, so the page loads each framework bundle up front. That constraint is the reason the API takes a whole file map.
Bulma takes a second or two here and USWDS a handful, against 0.35 s and 1.5 s for the native binary on the same machine. The compile is doing the full job each time, not a cached or partial one, which is why the timing moves with the framework you pick.
The preview frame loads USWDS fonts and icons from jsDelivr, because those are the asset paths USWDS's own settings point at.
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