Method: Helps `removeUnmatchablePseudoComponents()` replace or remove a selector `:not(.

Method: Checks whether there is at least one matching element for $cssSelector.

Method: Returns CSS content.

Method: Drops a media query type from the allowed list.

Method: Creates a DOMDocument instance from the given HTML and stores it in $this->domDocument.

Method: Adds a selector to exclude nodes from emogrification.

Method: Returns the HTML with added document type, Content-Type meta tag, and self-closing slashes, if needed, ensuring that the HTML will be good for creating a DOM document from it.

Method: No longer excludes the nodes matching this selector from emogrification.

Method: Applies $this->css to $this->domDocument.

Method: Parses the document and normalizes all existing CSS attributes.