anchor.diff:    (bind-vars bindings
       (apply #'compile-sheet body)))
   
  +(define-special-attribute font-family (&rest faces)
  +  (list (list :attribute "font-family" (format NIL "~{~a~^, ~}" (mapcar #'resolve faces)))))
  +
  +(defmacro define-attr-comparator (comp)
  +  `(define-special-selector ,comp (attr value)
  +     (loop with out = ()
  +           with values = (compile-selector value)
  +           for attr in (compile-selector attr)
  +           do (loop for value in values
  +                    do (push (format NIL ,"[~a~a~a]" attr ,(string comp) value) out))
  +           finally (return (nreverse out)))))
  +
  +(define-attr-comparator =)
  +(define-attr-comparator ~=)
  +(define-attr-comparator *=)
  +(define-attr-comparator $=)
  +(define-attr-comparator ^=)
  +(define-attr-comparator /=)
  +
  +(defmacro define-single-arg-selector (name)
  +  `(define-special-selector ,name (arg)
  +     (loop for arg in (compile-selector arg)
  +           collect (format NIL ":~a(~a)" ,(string-downcase name) arg))))
  +
  +(define-single-arg-selector dir)
  +(define-single-arg-selector lang)
  +(define-single-arg-selector not)
  +(define-single-arg-selector nth-child)
  +(define-single-arg-selector nth-last-child)
  +(define-single-arg-selector nth-last-of-type)
  +(define-single-arg-selector nth-of-type)
  +
   (defun generate (in &key (out (merge-pathnames (make-pathname :type "css") in)) (pretty NIL) (if-exists :supersede))
     (let ((eof (gensym "EOF")))
       (with-open-file (outstream out :direction :output :if-exists if-exists)
  
positive.code: 
  (define-special-block import (url &rest media-queries)
    (list (list :attribute (format NIL "@import ~a~{ ~a~}"
                                   (selective-downcase url)
                                   (mapcar #'selective-downcase media-queries)))))
  
  (define-special-block keyframes (identifier &rest body)
    (let ((inner (apply #'compile-sheet body)))
      (list (cons :block
                  (cons (list (format NIL "@keyframes ~a" (selective-downcase identifier)))
                        inner)))))
  
  (define-special-block media (selector &rest body)
  
negative.code:          ,@body))))
  
  (define-special-block charset (charset)
    (list (list :attribute (format NIL "@charset ~a" (resolve charset)))))
  
  (define-special-block document (selector &rest body)
    (let ((inner (apply #'compile-sheet body)))
  