From the W3C spec on CSS: "The expectation is that binding-specific casting methods can be used to cast down from an instance of the CSSRule interface to the specific derived interface implied by the type."
The stylesheet object represents the stylesheet itself. A stylesheet contains any number of separate rules, which can be manipulated with the cssRule (see DOM cssRule Object below).
Using the stylesheet object, you can add and delete style rules. You can also travel the hierarchy of stylesheets that can be associated with a particular document using the parentStyleSheet property.
Returns all of the CSS rules in the stylesheet as an array. This property indicates whether the current stylesheet has been applied or not. Returns the location of the stylesheet. Specifies the intended destination medium for style information. Returns the node that associates this style sheet with the document. If this style sheet comes from an @import rule, the ownerRule property will contain the CSSImportRule. Returns the stylesheet that is including this one, if any. Returns the advisory title of the current style sheet. Specifies the style sheet language for this style sheet.
Deletes a rule from the stylesheet. Inserts a new style rule into the current style sheet.