CSSRule

CSS object model css-object-model

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

niso: Partial 55%. 123 of 221 subtests pass, by system: Linux 55%, macOS 55%. 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 · CSS, CSSConditionRule, CSSGroupingRule, CSSMediaRule

CSSRule is an interface in idl/cssom.webidl, 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
CSS object model	Widely available	Partial 55% 123 of 221 subtests pass	4

Members

cssText

attribute

attribute DOMString cssText;

int32_t niso_css_rule_get_css_text(niso_dom* dom, niso_handle self, niso_str* out);
int32_t niso_css_rule_set_css_text(niso_dom* dom, niso_handle self, const char* value, size_t value_len);

parentRule

attribute

readonly attribute CSSRule? parentRule;

int32_t niso_css_rule_get_parent_rule(niso_dom* dom, niso_handle self, niso_handle* out);

parentStyleSheet

attribute

readonly attribute CSSStyleSheet? parentStyleSheet;

int32_t niso_css_rule_get_parent_style_sheet(niso_dom* dom, niso_handle self, niso_handle* out);

type

attribute

readonly attribute unsigned short type;

int32_t niso_css_rule_get_type(niso_dom* dom, niso_handle self, uint16_t* out);

STYLE_RULE

const

const unsigned short STYLE_RULE = 1;

CHARSET_RULE

const

const unsigned short CHARSET_RULE = 2;

IMPORT_RULE

const

const unsigned short IMPORT_RULE = 3;

MEDIA_RULE

const

const unsigned short MEDIA_RULE = 4;

FONT_FACE_RULE

const

const unsigned short FONT_FACE_RULE = 5;

PAGE_RULE

const

const unsigned short PAGE_RULE = 6;

MARGIN_RULE

const

const unsigned short MARGIN_RULE = 9;

NAMESPACE_RULE

const

const unsigned short NAMESPACE_RULE = 10;

KEYFRAMES_RULE

const

const unsigned short KEYFRAMES_RULE = 7;

KEYFRAME_RULE

const

const unsigned short KEYFRAME_RULE = 8;

SUPPORTS_RULE

const

const unsigned short SUPPORTS_RULE = 12;