CSSRule.parentRule
 The parentRule property of the CSSRule interface returns the containing rule of the current rule if this exists, or otherwise returns null. 
Syntax
var parentRule = cssRule.parentRule
Values
- parentRule
-  A CSSRulewhich is the type of the containing rules. If the current rule is inside a media query, this would returnCSSMediaRule. Otherwise it returns null.
Example
@media (min-width: 500px) { .box { width: 100px; height: 200px; background-color: red; } body { color: blue; } }
let myRules = document.styleSheets[0].cssRules; let childRules = myRules[0].cssRules; console.log(childRules[0].parentRule); // a CSSMediaRule
Specifications
| Specification | 
|---|
| CSS Object Model (CSSOM) (CSSOM) # dom-cssrule-parentrule | 
Browser compatibility
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
| parentRule | 1 | 12 | 1 | 9 | ≤12.1 | 1 | 1 | 18 | 4 | ≤12.1 | 1 | 1.0 | 
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    https://developer.mozilla.org/en-US/docs/Web/API/CSSRule/parentRule