Package selector contains a css3 selector parser.

package tokenizer tokenizes a css stream.

AtRule is an AtKeyword an optional param and an SimpleBlock.

BlockItem contains one and only one of DeclarationList, *Ruleset, or *AtRule.

Declaration is a Property and Value pair.

Ruleset is a selector followed by a Declaration Block.

SimpleBlock contains a list of BlockItems.

Statement is either a Ruleset or an AtRule or a comment.

Stylesheet is a list of Statements.

DeclarationList is a list of Declarations forming a block.