CSSRule
String selectorText
The selector text that specifies the document elements this style rule applies to. Setting this property raises a DOMException with a code of NO_MODIFICATION_ALLOWED_ERR if the rule is read-only, or a code of SYNTAX_ERR if the new value does not follow CSS syntax rules.
readonly
CSSStyleDeclaration
style
The style values that should be applied to elements specified by selectorText.
This interface represents a style rule in a CSS style sheet. Style rules are the most common and important kinds of rules in style sheets: they specify style information that is to be applied to a specific set of document elements. selectorText is the string representation of the element selector for this rule, and style is a CSSStyleDeclaration object that represents the set of style names and values to apply to the selected elements.