CSSSupportsRule
An object representing a single CSS @supports at-rule. It implements the CSSConditionRule interface, and therefore the CSSRule and CSSGroupingRule interfaces with a type value of 12 (CSSRule.SUPPORTS_RULE).
interface CSSSupportsRule extends CSSConditionRule {}
var CSSSupportsRule: {
prototype: CSSSupportsRule;
new (): CSSSupportsRule;
};