void parseExternal(String atRule) throws CSSException {
// @external .foo, bar; Drop the dots and commas
String[] parts = atRule.substring(10, atRule.length() - 1).replaceAll(
"(, *)|( +)", " ").replaceAll("\\.", "").split(" ");
CssExternalSelectors externals = new CssExternalSelectors();
Collections.addAll(externals.getClasses(), parts);
addNode(externals);
}