adam@29: class attr
adam@29: val attr_string : attr string
adam@29: val attr_int : attr int
adam@29: val attr_url : attr url
adam@29: val valu : t ::: Type -> attr t -> t -> css_value
adam@29: 
adam@29: val prop1 : t ::: Type -> attr t -> string -> t -> css_style
adam@29: val prop : string -> list css_value -> css_style
adam@29: val props : list (string * list css_value) -> css_style