The read-only style property is the CSSStyleDeclaration interface for the declaration block of the CSSStyleRule.

A CSSStyleDeclaration object, with the following properties:

computed flag

Unset.

declarations

The declared declarations in the rule, in the order they were specified, shorthand properties expanded to longhands.

parent CSS rule

The context object, which is an alias for this.

owner node

Null.

The CSS includes one style rule. This will be the first CSSRule returned by document.styleSheets[0].cssRules. myRules[0].style therefore returns a CSSStyleDeclaration object representing the declarations defined for h1.

h1 {
  color: pink;
}

let myRules = document.styleSheets[0].cssRules;
console.log(myRules[0].style); // a CSSStyleDeclaration representing the declarations on the h1.