CSSImportRule

@import import

Baseline: Widely available on the web, in every major browser since Jul 2015, and long enough to count on (since Jan 2018).

niso: Partial 73%. 28 of 38 subtests pass, by system: Linux 73%, macOS 73%. Engines: QuickJS, the engine niso's WPT run uses; Node and Porffor have no recorded run. WPT results recorded at f3b4fa8, 2026-11-10; web-features 3.45.0. WPT tests · niso's support · CSSImportRule

CSSImportRule is an interface in idl/cssom.webidl, inheriting CSSRule, exposed in Window. What it does is on MDN; this page says what niso has of it.

Status

The web features its members belong to, each with its Baseline status on the web and how much of the feature’s WPT suite passes in niso (see Web platform support).

Feature	On the web	In niso	Members
@import	Widely available	Partial 73% 28 of 38 subtests pass	2

Members

href

attribute

readonly attribute USVString href;

int32_t niso_css_import_rule_get_href(niso_dom* dom, niso_handle self, niso_str* out);

Not in niso yet

Members the web has, by the BCD keys web-features 3.45.0 lists, that idl/ doesn’t declare. The list is partial: web-features lists only the keys it maps to a feature.

• layerName (Cascade layers)
• media (@import)
• styleSheet (@import)
• supportsText (@supports)